Advice on Creating Montage of TV Advertisements
As a person who works for TV and does commercials on a regular basis, I'm afraid to tell you that a youtube-rip is probably your best option. The progress for a commercial usually goes like this:

You've got your customer. The customer speaks to an agency. That agency usually hires a production-company that actually makes the commercial. After that, the final files (usually prores 4444, 422 or rarely an h.264) will be transmitted to the customer for approval, and then go directly to the TV-Station which will broadcast the piece.

So from someone who is not directly part of the creating-progress, it's virtually impossible to get your fingers on the final files. Your best chance would be to ask politely, but I can tell you that those files are almost always exclusive to the people working on it.

Your best option might be to record the signal directly from the TV via something like an elgato capture card. If that doesn't work (or you don't want to spend the money on the hardware required) youtube and reuploads are your only option.