Reddit videos not playing?

Hi,
I don't use that extension but those sites you mentioned all work fine on Edge when I try them (from stable to canary). and I have Tracking prevention set to strict, I have ublock origin and bunch of other extensions.

if the problem only happens on Dev channel, please file a feedback using feedback button on Edge, but if it also happens on other channels, you might want to contact that extension developer and let them know about this issue.
even though Chromium browsers do share the same HTML and Javascript engines, they can still be very much different from each other.
user settings in Edge can also be a reason for that issue.
you can reset them from here: edge://settings/reset
and in case you are using any flags, you try setting them all back to their default values
edge://flags/