In short, don’t panic, this is normal (by YouTubes standards) and you have nothing to worry about.
YouTube ContentID checks all videos for copyrighted content. This has nothing to do with Slipmat as you stream goes trough YouTube and is only embedded on Slipmat. Everything regarding the stream itself is a matter with YouTube.
These copyright notices have no affect on your channel whatsoever. As the email message says, YouTube can 1) put ads on the video, 2) block the video on some countries and/or 3) mute the video. Again, these actions have no affect on your channel whatsoever, they only affect the video in question.
The best and easiest way around the dumb copyright issues (ie. the pointless emails you get) is to delete your stream recording after your stream has ended - that’s it, done. If you want to record your video performance, record it on your local machine so you get best possible quality also.
There is nothing you can do about the video to not be scanned by YouTube. They do it for every single video no matter the settings or visibility status or length or any other attribute. Again, easiest way to go around this is to just delete the archived video after your set. Its an annoyance but it works and only takes 10 seconds of your time.
Read The difference between copyright takedowns and Content ID claims on YouTube.