Comment by MobutuPehuenche

I would think this is common practice.

I know that YouTube, for example, retains videos indefinitely, because I've personally been able to retrieve videos that were deleted in as early as 2006.

It was possible for anyone to do this until some time in 2017, when they started requiring signatures for RTSP streams. All that was needed was the video ID (the eleven characters in every YouTube video URL). Didn't matter if they were private (IDs for these could be enumerated if the channel ID was known), "deleted" over ten years ago, or behind a paywall.

From ~2008 until 2015, you could do the same but with higher quality streams through the now-retired Apple TV API.