If you do a search on Google Video, which now is a video search engine and returns content from YouTube and Google Video, you'll notice an option to watch each video result on the same page, in a small player. This is a good way to preview the content before watching it in full view.
If you have a slow or unreliable Internet connection, you can open more videos at the same time and pause all of them, so that you can watch the videos without interruptions.
Google tested the video PlusBox in the web results, but probably realized that it's more appropriate to use it in Google Video.
14 minutes ago