Apparently, you're not familiar with reaction videos on Youtube. Be that as it may, you seem to have missed my point. If I let the video I"m commenting on run to its end, Youtube plays another video automatically. That's to be expected. What's not expected is that after that happens, my Browser Source no longer plays the video I selected. That seems rather odd to me.
For example, I entered this url into the Browser Source URL line:
https://www.youtube.com/watch?v=SEPgBVlRfZo
Then I let the video play through the end so Youtube would start a new video. Then I hit Refresh. Instead of playing the video from the URL above, it began playing the video that Youtube cued up. If I then look at the Browser Source URL fiield, this is what I see:
https://www.youtube.com/watch?v=SEPgBVlRfZo Notice that the URL has not changed. And yet OBS is playing the new video.
If I refresh the cache, it still plays the second video. There is no way for me to return to the video I want except to delete the source and recreate it or close OBS and reopen it. ISTM that OBS ought to only play the video from the URL that is entered into the URL field.