But basically, I have nothing to lose by posting my video, right? Worst thing that happens is they take it down.
It's not like I'm making money off of it.
Youtube have an automatic content detection system, so if you have used a song clip, there is a reasonable chance that it will be recognised, and the advertising/publication policy on your video given to the company that registered the material that was used. The material will also automatically be acknowledged on the video's page.
If the original publisher simply want advertising and revenue, then they can ask youtube to place automatically, their details on your video page; youtube will also place adverts on your video, and provide them with the revenue from them.
Similarly, if the original publisher want your video blocked in certain countries, it will automatically be blocked. If they want unskippable 2 minute advertisements before your video, they can have it. If they want the video blocked on mobile devices and adblocked PCs, then they can have it, etc.
Alternatively, if the content publisher are being dicks, then they can ask youtube to place a "copyright strike" against your account. Too many of these, and your account is terminated and videos deleted.
If you have a legitimate license to use the content, then when you receive notification of a content match, you should submit your license to youtube using the copyright notification system. If the publisher agrees that your license is valid, control of your video will be returned to you.