DCMA take down only works on sites that honor DCMA.
DCMA services can only go after sites they can find and or sites they know about.
And even then, only if they have access.
And even then, only if they can get through the hoops to find and report all the videos.
DCMA services tend to charge a noticeable fee, Often per video.
Having to spend money to stop some thing some one else does for free or for profit is economically a loosing battle.
Honestly I think the best way to fight piracy is to break their business model.
For instance, if your videos are on pornhub. The viewer gets the video for free, you get money on the advertisements. And there really is no reason for any one to pirate your video.
FYI pornhub does offer a DCMA service. but I really don't know how good or bad it really is. Long term, I think a company like pornhub is probable in a better place to do effective DCMA. Because if they do DCMA, they're probable going to do it in a large scale automated fashion. But I don't think they're there yet.
If your going to embed a DCMA logo into your stream. Put it into the stream using your encoding program. On some thing like CB, that's going to be OBS. Don't try to put it on top of the stream using HTML/CSS, that shit doesn't work.
You can also uses some thing like OBS to embed your cam name into the stream. At least then pirated content will at least promote you.