I made a little collection of great channels on Youtube. If you'd like to create a video lesson, but you don't know where to start, just check out any of these channels and find a video for your lesson.
I grouped the channels into various categories, like animation shorts, clips from animated movies, documentaries, TED talks, etc.
My favorite channel: Fandango movie clips. I like it because it is a well established channel and videos don't get deleted, and the scenes are very well selected: https://www.youtube.com/channel/UC3gNmTGu-TTbFPpfSs5kNkg
Indie films: https://www.youtube.com/user/FilmFestivalVideos/videos
Animation: Animation https://www.youtube.com/channel/UC6nsfayf5ZTWp228Ry2wI7Q/videos
Stories for learners of English: https://www.youtube.com/channel/UCHD0-6opjI0paLJj6P-f2sA
My absolute favorite: TedEd - 5 minutes, unique videos answering interesting science and social questions:
TedEd: https://www.youtube.com/user/TEDEducation/videos
Ted Talks: https://www.youtube.com/user/TEDtalksDirector
Chris Hadfield about life in space: https://www.youtube.com/playlist?list=PLPfak9ofGSn9vOEkIz328i4xQQq7e0kjc
Last Week Tonight with John Oliver: https://www.youtube.com/user/LastWeekTonight
Mental Floss Video https://www.youtube.com/user/MentalFlossVideo
Hip Hughes History https://www.youtube.com/user/hughesDV
The Talko Celeb Videos https://www.youtube.com/channel/UC1Ydgfp2x8oLYG66KZHXs1g
CPG Grey explaining the world https://www.youtube.com/user/CGPGrey
Smarter Every Day https://www.youtube.com/channel/UC6107grRI4m0o2-emgoDnAA
Geography Now https://www.youtube.com/user/GeographyNow
Science and engineering videos https://www.youtube.com/user/1veritasium
Popular Science Show https://www.youtube.com/user/scishow
Science Show Kids https://www.youtube.com/user/scishowkids
Crash Course Science and social https://www.youtube.com/user/crashcourse
Crash Course Kids https://www.youtube.com/user/crashcoursekids
Science https://www.youtube.com/user/itsokaytobesmart
Animals https://www.youtube.com/user/Anmlwndrs
Science and stories about our aawesome planet https://www.youtube.com/user/minuteearth
Matthew Santoro https://www.youtube.com/channel/UCXhSCMRRPyxSoyLSPFxK7VA
WatchMojo https://www.youtube.com/user/WatchMojo
Commoncraft https://www.youtube.com/user/leelefever/videos
In59seconds https://www.youtube.com/user/In59seconds/videos
1-minute personal stories: https://youtu.be/pGa1nNzcrqU?list=PLYuixBIhmyjJo2pDxMTYSsAVsLmvU6X4n