I have noted that videos taken with a camera have very high bitrate e.g. 10000kbps for 720p/1080p videos. But YouTube Videos in these resolutions have comparatively less bitrates for the same resolutions e.g. 2000-3000 kbps but there is not a lack of clarity always. I have a Tech Com TV Tuner the minimum bitrate is 1000kbps for a 352x288 video yet the video appear pixelated.
To answer your actual question, open the video in a player such as VLC, then go to Tools > Codec information or whatever is the equivalent in other media players.
Standard minimum video bitrate requirements based on popular encoders as follows:
480p- 1500-2500kbps
576p- 2500-3500 kbps
720p- 5-8 mbps
1080p- 10-12mbps
2160p- 18-24mbps
These are the minimum to get a non-pixelated video on various resolutions sometimes bitrate requirement goes beyond the limit if the source is grainy
That is because those youtube videos are encoded using very high efficiency encoders running on powerful hardware. Your techcom tv tuner doesn't even come close.
