When does archive.org(waybackmachine)archive Youtube videos?

This is something I've wondered for a long time. I've seen others ask around about it and no one really can give a answer, I have no idea if it's random or not because some videos will and some won't. Hardcore archivers talking in a way that isn't straighforward doesn't help. I'd love if it could be explained one day because it would be really helpful

Either way, the best way to archive a video or series of videos is to download it (using youtube-dl can let you download a whole channel) and uploading that to the video portion of their site

Could this mean that we can find videos that have been deleted? I might be well off so correct me if I'm wrong.

I'd wish, but it seems to be absolutely random at which time it actually does it. For example, the Sid the Science kid lost episode had to be found another way. The Youtube page was archived, but not the video in the page. 

My personal encounter with archived YouTube videos is when I found this video and similar sets from 2007.

In this case, no audio was saved. I was able to download the video as an flv (YouTube - Dirge of Cerberus Steath mission.flv) which is a flash-compatible video file.

The YouTube player is definitely programmed differently nowadays, in such a way that the Wayback Machine is not programmed to archive. My speculation is that this has to do with YouTube possibly moving away from flash and Java, but I can't back this claim up.

One thing that irks me is that today the Wayback Machine plugin can't properly save YouTube pages. All that get saved is a blank page. No text, no video, nothing.