Unique alphanumeric strings like the one you provided are frequently used for: for private video streams.
Typically consumes 1.2 GB to 2.7 GB of data per hour.
I paid for YouTube premium, why am I stuck on 720p? - Google Help
If you are viewing content in 720p, you are watching in , which is the baseline standard for modern video quality. Resolution: 1280 x 720 pixels. Aspect Ratio: 16:9 (Widescreen).