The bike in the video is a 2002-07 CR250. It's an RC valved engine as evidenced by the large
cable cover on the left side forward on the cylinder and the frame is a gen 3 due to the "2X4"
main spars - in other words, an OE CR250 ridden by a pro. It is not a gen 5 (2010 or later)
CRF250 frame.
Regarding your question, the swap can be done. I'm just starting a similar project myself.
The only problem is wether to use the gen 5 or a gen 4 frame. The gen 5 takes advantage of
the new short body rear shocks but Honda has yet to get the geometry right. So far the best
handling Aluminum frames are the 2008-09 which are gen 4s, that's the frame I used for my
CR500 conversion.
If you still want to procede with a 2010 or later frame, pm me and I will fill you in on all the
mods that need to be done.
dogger