I created a 3 second toon for the sole-purpose of seeing what kind of problems I'd encounter. And right off the bat, as soon as I uploaded it to YouTube, a few of the frames get "stuck", aka, just acting a little glitchy.
See how when the character goes down, his head just sticks? Why does that happen? How can I fix that? FYI, it's not like that at in the original timeline.
Bonus question: Why does the exported video have fuzzy/bad sound quality? How do I fix that too?
You exported straight from Flash as a movie?
I usually don't get good results when exporting something as a movie. What I do is export as a PNG sequence, and use some other program like Premiere or After Effects to composite and create a video file.