: Refers to the color depth. 10-bit encoding allows for over a billion colors, significantly reducing "banding" in gradients (like skies or shadows) compared to standard 8-bit files.
Most likely because the ripper used the stereo audio track to save space. Some WEBRips incorrectly drop the 5.1 track. Look for DDP5.1 in the filename if you want surround. 365.Days.2020.1080p.10bit.WEBRip.DDP2.0.x265.HE...
Enthusiasts might seek 10bit x265 WEBRip for: : Refers to the color depth