Share video feature

### Your use case

#### What would you like to do?
I'd like to share a youtube video that plays locally for all participants synchronized.

#### Why would you like to do it?
I organize meetups in which we have such a shared video of a lecture, and anybody can play/pause and then we discuss what we watched. Also I use this feature for a shared exercise/workout video.

#### How would you like to achieve it?
Both Jitsi and BigBlueButton currently have that feature, I'd do it the same way as they do.

### Have you considered any alternatives?

I currently use Jitsi instead and I would prefer using Element.

### Additional context

_No response_