What extra features has the Android Youtube application over the HTML one? It seems the HTML Youtube application has all the features the Android Youtube application has. I want to remove the Android Youtube application. But I want to make sure that I will not lose any feature.

Do you know if the installed Android Youtube application has any extra features that the web Youtube does not have?
You shouldn't lose any viewing features. The YouTube application is simply a way to make it easier to view and search, without having to load the entire html pages. Probably the only feature you wouldn't be able to take advantage of (and i don't know this for sure) is uploading. You can use the YouTube app to upload videos you've taken to your own YouTube account. And like i said, you might be able to do this through the browser, but the app is just a way to make it easier. Simplification is key.