Anecdotally I've noticed that higher quality videos, whether be a 1080p HD video on the TV or a BluRay rip on a computer, the volume seems to be lower than a standard quality video. I've noticed this since at 100% volume of several really high quality video's its still difficult to hear while 100% volume of lower quality videos is deafeningly loud.
Why is this? Is there a technical reason? Is it assumed that high quality videos will be played on high quality speakers which go louder?
The longer answer is that you can increase the perceived loudness of a track by applying lots of audio compression (not to be confused with data compression on the audio file). Compression evens out the loud and soft sounds, and then you typically normalize the track so that the largest peaks are just short of clipping. The end result is very loud, but you have thrown away all the dynamics in the original material.
You don't mention the specific media or format by which the video is delivered. HD video may contain surround sound encoded audio, and you might not be hearing all the channels, dpending upon your speaker setup.
Speakers have a much higher audio quality at 85% volume than 100% because near maximum volume, the speaker's internal hardware's equalizer boosts frequencies near 4 kHz to produce artificial loudness (as known from loudness wars), which leads to loss of audio vibrancy.