step 1 is gonna be dont share it through youtube. Google processes the video and compresses it to save space. The pixels we get on youtube are not the pixels that are on your original video file.
Step 2 is open the video in VLC and use the interactive zoom feature. Its not very intuitive at first. But once you get the hang of it, it works pretty well. Then go through the video slowly and you can usually piece together license plates. Usually you dont get the entire plate from a single still frame.
ETA - I downloaded youtube's 1080p stream. I think I can make out "4S7623". Something is in front of the 4. Not sure if its a digit or part of the license plate design.
We may be able to get it nailed down better if you can share the original video file.