Video content creators who talk about anything not approved by the establishment don't get ad revenue from their content. Youtube will still play the ads on their videos, but keep all the ad revenue. The only way those content creators can make any money off of making content is through advertisers that sponsor the videos, where the content creator will shill for the service or product in video. It's extremely common for guntubers, homesteaders, and anyone to the right of Stalin.

All a government would have to do is "sponsor" a video for a content creator, lie about where the money comes from, and bam, you magically have "foreign influence", and the content creator unknowingly becomes a "foreign agent". There would be no realistic way for a content creator to vet where the money comes from. Most are usually just happy to pay the bills, as Youtube actively censors their content and prevents it from gaining the traction it otherwise would, due to the "algorithm", just like Google does with wrongthink.