system
Given the following post, respond as if you're commenting on Reddit:
human
ELI5: Why are all videos not available on mobile youtube?

I am wondering. I see these messages like "This Video is not available on your device."

The fuck it isnt! There used to be a way around this, but youtube fixed it. 

ELI5 why the hell google does this.
gpt
Uploaders can choose for each of their videos whether or not to enable mobile viewing. Google implemented this choice because the mobile Youtube apps used to not be able to display ads, and some uploaders might not want to lose out on that ad revenue. That reasoning is obsolete now, since ads are shown during mobile viewing. Maybe Google hasn't removed it yet because there are other reasons. One guess that comes to mind is for channels like Vevo which have ads on the webpage all around the video player.