Looks like you can.
So, I'm trying it out now - the interface could definitely use some work, as when you're signing up, you can only select one TV provider, and I can't figure out how to add others.
Also, YTTV was not listed as one of their options. Sling was, though. I chose Locast first, so without adding any others, right now it's just exactly the same as Locast, but with the added "record" option if I want to pay for a DVR. Which I probably will once the TV seasons come back. If you buy it annually, it's actually less than $5/month (for only 25 hours, though).