to possibly work in some other time:
Project-Fractal Cuts, some Vi Hart videos: http://www.youtube.com/user/Vihart
Comp Lab-Fractals
https://www.youtube.com/playlist?list=PLA34565411F0821C0 (watched #7, but there are lots more videos there).
http://www.dangries.com/Flash/Fractal MakerExp/FractalMaker_exp.html ,
http://math.bu.edu/DYSYS/applets/chaos-game.html
Project Mobius Strip (http://www.youtube.com/playlist?list=PLEC77462F1ECB5D3E )
Proofs: http://mathoverflow.net/questions/ 8846/proofs-without-words
http://www.artofproblemsolving.com/Wiki/ index.php/Proofs_without_words
Xactika: http://www.setgame.com/xactika/puzzle
Mistake Proofs
Music a different way: https://www.youtube.com/watch?t=59&v=Y5seI0eJZCg and https://www.youtube.com/watch?v=PoVTcr3RDEU
2048: http://gabrielecirulli.github.io/2048/
2048-Fibonnaci Version: http://www.crazygames.com/game/2584-fibonacci
Math Olympiad -https://www.imo-official.org/
Comp Lab-Logic Puzzles www.nikoli.com
Erik DeMaine video on origami: https://www.youtube.com/watch?v=PHXrRgmgMWg
Vi Hart Videos on Origami, and Counting.
a little discussion of the Pythagorean Theorem (http://www.mathsisfun.com/geometry/pythagorean-theorem-proof.html) and curve stitching (http://www.ams.org/samplings/curve-stitching and
http://britton.disted.camosun.bc.ca/string_art/jbstringart.html) and connections.
Maybe some work using the Countdown Numbers game: videos like: https://www.youtube.com/watch?v=pfa3MHLLSWI and newer version: https://www.youtube.com/watch?v=9eMs_o08Gm4
Computer apps to play Countdown: http://happysoft.org.uk/countdown/numgame.php or https://nrich.maths.org/6499
Maybe flextangles activities: https://www.youtube.com/watch?v=pta1R7g05Xg,
Perhaps something with spirographs: http://www.mathplayground.com/Spiromath.html, https://www.geogebra.org/m/d4duHF2C
Perhaps something related to a kaleidoscope: https://www.geogebra.org/m/FzjNYuV9, https://www.youtube.com/watch?v=wEhmFskODNc
Statistician videos: http://thisisstatistics.org/students/#statisticians, https://www.learner.org/courses/againstallodds/unitpages/index.html
TED talks on Math (many are too long to watch at camp): https://www.ted.com/playlists/189/math_talks_to_blow_your_mind, http://ed.ted.com/series/math-in-real-life
The Engineer Guy: https://www.youtube.com/results?q=engineerguy
Mathematical Moments: http://www.ams.org/samplings/mathmoments/browsemoments?cat=all, all have posters, some have a podcast with them.
NASA videos-From Hidden to Modern Figures: https://www.nasa.gov/modernfigures/videos
Math Olympiad -https://www.imo-official.org/
Videos with some problem solving techniques: https://www.youtube.com/playlist?list=PLxJxkVaCA_7IXPRdKjSzmr4Cpht1830cT
Books for working with young problem solvers: http://bookstore.ams.org/MCL
Mathematical Impressions videos: https://www.simonsfoundation.org/category/multimedia/mathematical-impressions-multimedia/, by George Hart. They also have science videos: https://www.simonsfoundation.org/category/multimedia/science-lives/
Videos on Math: https://www.youtube.com/channel/UCMpizQXRt817D0qpBQZ2TlA, https://www.youtube.com/channel/UC1_uAIS3r8Vu6JjXWvastJg,
https://www.youtube.com/user/MathsInspiration/videos, https://www.youtube.com/user/numberphile/videos ,
http://wild.maths.org/-mathematical activities and stories.
Maybe an activity from http://thewessens.net/ClassroomApps/index.html?topic=home# or http://www.celebrationofmind.org/?page_id=1346
Math in the movies: https://www.youtube.com/watch?v=_IZMVMf4NQ0&t=2s
Cryptography: http://www.simonsingh.net/The_Black_Chamber/index.html
The staircase pattern: https://www.youtube.com/watch?v=Kx6X7XGEJv0, polygonal numbers: https://www.youtube.com/watch?v=CxOapqYOhug&t=26s
Monty Hall Problem-https://www.youtube.com/watch?v=Zr_xWfThjJ0, https://www.youtube.com/watch?v=mhlc7peGlGg, http://www.shodor.org/interactivate/activities/AdvancedMontyHall/
Pascal's Triangle &:Sierpinski Triangle: 3 ways to generate: https://www.geogebra.org/m/wTrjBEaC, https://www.youtube.com/watch?v=04mXcF8FZps (can actually do by hand)or in 3D-https://www.geogebra.org/m/G5gvqWR9, https://www.geogebra.org/m/m5g8DPdJ or https://www.youtube.com/watch?v=droTYSmSGHg (takes too long to do by hand) but has an interesting reversal: http://math.bu.edu/DYSYS/applets/chaos-game.html (if the game will work as it uses old Java), or use Pascal's Triangle (https://www.youtube.com/watch?v=EE0ODmhiLlA&index=9&list=PLA34565411F0821C0)-which can also be done by hand and Menger Sponge: https://www.youtube.com/watch?v=fWsmq9E4YC0. https://www.youtube.com/watch?v=XMriWTvPXHI
Math Encounter videos, https://www.youtube.com/playlist?list=PLBC7544C3215C63A0, from the National Museum of Mathematics, http://momath.org/. They have a song competition and some songs are at https://www.youtube.com/playlist?list=PLvBeH0oPsOMVFKWPuzkBu_s9JXGt3fVrh
http://www.nbc.com/americas-got-talent/video/nick-uhas/3529877 from America's Got Talent. He also has other videos at https://www.youtube.com/user/NickUhas/featured.
The Simplest Impossible Problem: https://www.youtube.com/watch?v=m4CjXk_b8zo
a little discussion of the Pythagorean Theorem (http://www.mathsisfun.com/geometry/pythagorean-theorem-proof.html) and curve stitching (http://www.ams.org/samplings/curve-stitching and
http://britton.disted.camosun.bc.ca/string_art/jbstringart.html) and connections.
Demo Sum of All Thrills- http://mathmovesu.com/games/sum-all-thrills , roller coaster design: http://puzzling.caret.cam.ac.uk/flash/roller.swf (no longer works), so did http://dep.disney.go.com/sodi_app/and http://discoverykids.com/games/build-a-coaster/ , where we intentionally made mistakes just to see what happens
Logic Puzzles www.nikoli.com
Demo For the Win (https://www.artofproblemsolving.com/ftw )
Walk the Line (the idea that graphs tell stories--http://www.graphingstories.com/) ,
WWTBAM using problems from http://tube.geogebra.org/student/b138355 or problems on infinity (starting with various problems from https://www.khanacademy.org/math/algebra-home/precalculus/seq-induction and moving to some videos on infinity. Hilbert's Infinite Hotel: https://www.youtube.com/watch?v=Uj3_KqkI9Zo
Vi Hart video on .9999 https://www.youtube.com/watch?v=TINfzxSnnIE and her April Fool's video on .999
Zeno's Dichotomy Paradox: https://www.youtube.com/watch?v=EfqVnj-sgcc, Five Really Big Numbers: https://www.youtube.com/watch?v=TykhPbzmyek, not enough time to watch a whole series of videos on Ridiculously Huge Numbers: https://www.youtube.com/playlist?list=PL3A50BB9C34AB36B3)
Maybe continued fractions: https://www.youtube.com/watch?time_continue=6&v=QAMXSU40ZgA
Mathemagician: https://www.youtube.com/watch?v=M4vqr3_ROIk and https://www.youtube.com/watch?v=-LALMbu4vPE
Estimation-perfect squares: https://www.youtube.com/watch?v=1JW9BA57aR8 or https://www.youtube.com/watch?v=_eFhrnZxAgU (about minute 19 he starts explaining how he is doing the mental math).
A model for multiplying polynomials or squaring numbers: https://www.brightstorm.com/math/algebra/polynomials-2/multiplying-polynomials-using-area-models/ or https://www.khanacademy.org/math/algebra/introduction-to-polynomial-expressions/multiplying-binomials-2/v/area-model-for-multiplying-binomials
Demo For the Win (https://www.artofproblemsolving.com/ftw )
Curriculum Inspirations: http:/maa.org/ci many videos over AMC contest problems organized by problem solving strategy or by NCTM Content Standard.
Vi Hart video on .9999 https://www.youtube.com/watch?v=TINfzxSnnIE and her April Fool's video on .999
Zeno's Dichotomy Paradox: https://www.youtube.com/watch?v=EfqVnj-sgcc, Five Really Big Numbers: https://www.youtube.com/watch?v=TykhPbzmyek, not enough time to watch a whole series of videos on Ridiculously Huge Numbers: https://www.youtube.com/playlist?list=PL3A50BB9C34AB36B3)
Twin Prime Conjecture: https://www.youtube.com/watch?v=6yrEA5hs-hk
The simplest impossible math problem: https://www.youtube.com/watch?v=m4CjXk_b8zo
Dr. Hopkins YouTube channel with math songs: https://www.youtube.com/playlist?list=PLgQhuyBS3_qb65_uFn4dJ-5_tsuQL-vjS