Certainly looks and sounds like a sticky throttle cable.
First adjust cable for minimal free play then look at the cable where it joins the throttle body and see if you can see any movement at all after you let go of the throttle on the handlebar.
When the revs get stuck on 3k rpm, push the throttle body cable connection drum with your finger and see if the revs drop immediately that you push on the drum. If it does then you have a sticking cable or throttle body.