Hello there.

Is there a way to change resolution or something, because when I increase the zoom, the characters lose a lot of detail (they look a little blurry). They had lot of detail, back in the day at 800x600 on a CRT monitor.

Also, there is a way to remove the movie played when selecting Shadow's of Amn, Throne of Bhall or that Black Pit?

If you were to play at 800x600 (OG or EE edition) you would see it looks blurry on a LCD/LED display. CRTs working differently "hide" that blurriness. So, basically, you can't make a current display look similar to a CRT one.

As for removing the movies, you mean the opening movies, right? I believe you can skip them with a config file change or something but I'm not that experienced with it to confirm.

BG2 uses 2D graphics as was common back then. The sprites used by the game have a fixed resolution. Graphics cards and monitors might use tricks to hide the blockiness, but there's no way to improve the resolution of the sprites without creating new ones at a higher resolution.