Why is the desktop web version so limited?

I was trying to watch some clips on my computer earlier and realized how annoying the web layout is. there is no way to watch stuff in landscape or expand the video past that narrow phone column.

Plus the left menu and all the like and share buttons stay right on top of the video the whole time with no way to hide them.

Does anyone use a specific extension or browser trick to make watching on a pc a bit cleaner, or is this just how it is?