[lnanek2]

Isn't there a population shift, though? The users who will install an extension for this have different tastes than the users who won't, so you can't assume the like-dislike ratio for the population who will matches the population who won't.

[gus_massa]

Moreover, it will be easier to brigade (or shill). If a video has 1M upvotes in YouTube and 1K upvotes in the site, then with 1K enthusiast you can tilt the count. (And for obscure videos with 100 or 1000 less upvotes in YT, it will be easier.)

[soledades]

If not many people use it, there will be much less incentive to shill

[soledades]

But maybe the signal is even better in the subpopulation