Streaming can provide decent quality, but not high quality. That's simply too costly on scale.
Bit rate alone doesn't necessarily tell you quality either.
I suggest you look for downloads and look for
- Release Groups that match your intentions (once you found favorites you may want to stick to them)
- Screenshots on releases/info pages
- Encoding information
To assess encoding information, you look at file type, video codec, and encoding bit-ness.
From high to low compatibility, and low to high compression ratio:
- mp4 file, AVC/x264/h.264
- mkv file, HEVC/x265/h.265
- mkv file, HEVC, 10-bit
- mkv file, AV1 [10-bit]
You can consider the triplets of the codec to be different names for the same thing.
You'll be able to play all file and codec types on a PC, but not necessarily on other devices. If you're streaming from PC to something else, that's fine too.
I'm usually looking for 10-bit HEVC releases because of their vastly superior size for quality. If that's not available, HEVC or AVC. In most cases, it doesn't matter too much to me.
A video with a lot of movement or visual detail will have bigger sizes.
If you compare an AVC release and bitrate with a HEVC 10-bit release and bitrate, they are vastly different. You can get the same quality for a fraction of file size and bitrate. More bitrate is often a waste of bandwidth and storage space.
Any form of audio and video uses codecs. It applies to streaming websites as well. It's usually technological details that is not obviously disclosed to users for simplicity/convenience.
It's possible to inspect the stream and media, and find out what is being used. It may offer alternative streams, to support more efficient modern and less efficient older platforms.