I believe they are flash based so you must have flash, as long as that lasts...
How do you get flash
Is it gonna destabilize my device?
Depends which phone. All videos are viewable on my s3.
?
Flash isn't supported on all devices.
Not true, it is simply no longer available but if you sideload it will work (as of now).
Nope. It never worked on the Optimus S.
CMIIW, but I think that flash was available on android 2.1 thru 4.0