^You are loosing definition, especially with the stars in the first picture (though Dax does look cuter), and though your edit is more refreshing than the original, it not really needed.
Uploading that specifically to YouTube reduces the entire movie to the enlarged format's true resolution.
When cropping the video for 16x9, keeping as much head room as possible would be my preference. Here, Garak's head is chopped off a bit. In this case, I would crop more from the bottom. Though I realize there will be times that it's going to be unavoidable.
Instead of cropping, some prefer to distort the image so that it covers the format without losing anything.
Uploading that specifically to YouTube reduces the entire movie to the enlarged format's true resolution.