Lots of php mostly. A bit of node. We use python but we are small players.

The fun thing is more about the db. E.g some go full in memory redis while others stay on a good old mysql.

Although, don't let yourself fooled by the poor ui. It doesn't reflect the tech behind, and is now mostly ugly for marketting reasons.

Big sites makes millions and of course have full time dev team. They need to innovate constantly. E.g provide best moments on the player timeline, add face recognition to categorize actors, buff the infra for live cams, etc.

However, very few use the cloud. It's mostly home made. Video streaming is expensive, and you can divide your costs by 10 by avoiding aws and cie.