Issues playing Youtube videos in Hubs

[befriendabacterium]

Description
Youtube videos do not play smoothly from within Mozilla Hubs

To Reproduce
Steps to reproduce the behavior:

1. Go to https://hubs.mozilla.com/H7ysfZK/esmarconf-test/
2. Create an object with a link to an uploaded or live Youtube video (see examples I have tried below).
3. Go to the back of the main hall and pin the Youtube video there (see screenshot) to maximise it.
4. Try to watch the Youtube video.

Expected behavior
Video plays/streams smoothly, not lagging/seeming to buffer.

Screenshots

Hardware

• Device: Laptop (HP Elitebook)
• OS: Windows 10
• Browser: Firefox

Additional context

The non-live video i'm having trouble playing smoothly in hubs is here (https://www.youtube.com/watch?v=C6IFlRl3rzg) - it is quite a graphically involved presentation from last year's conference (we hope to use hubs for this year's conference).

The live video I tried is here (https://www.youtube.com/watch?v=9Auq9mYxFEE) and seems to stream better, interestingly - even though it's higher fidelity.

I am having these issues even though I'm the only one in the hub. It may be something to do with maximising the video on the back of the main hall.