This guy will explain them to you with video games and clips from Harry Potter. Part 1 is here, Part 2 is here.
Micah Howard of the Pittsburgh Symphony has a page with a lot of great basic technique videos. He developed an app he is selling on on the front page of his site, but you don't have to buy anything to get to the videos. Tons of super reminders about setup that will help you with your intonation and tone.
This site has video demonstrations of every bowing you'd ever want help with, lots and lots of familiar tunes for practicing shifting, familiar tunes designed to be played on one string, mixed up familiar tunes for rhythm practice and familiar tunes in multiple keys to really get your finger patterns down.
Georgia orchestra teacher Seth Gamba has a great series of lessons and resources on his YouTube page.
This YouTube Channel has a bunch of nice videos for teachers about bow hold, left hand and bow strokes. Try one of them as a personal review!
Here are some demonstrations of a variety of ways to get your vibrato jumpstarted! Cello/bass are at the bottom of the page.
Joanne May has been posting good videos to her YouTube channel. This is a nice, slow-paced bow hold review.