Yes, the I beams are 20 feet long. I took a whack at the bend radius and it looks like 33-36 inches.
The 14.5 deg offset doesn't seem too bad, until you start trying to control it and make a uniform radius without kinking it. I think it's doable though.
If you can bend it over your knee, I'm going to start calling you Mr. Neo!
As Tom pointed out, you're bending the easy axis, so the 5" web might not be much worse than the 4" if the flanges are about the same.
Hydraulic press is probably how I'd try it, since I have one. Looks like it works fine based on the video. I might try to spread the bend out more, but what he got looked pretty good.
I would encourage you to secure the rig better than the video shows. I've had 20 tons on something and had it come out of the press. Needless to say, I give it a lot of respect ever since. When you're bending (I wasn't), you create forces that tend to push the outer support blocks away from the center. Either use a buck that's solid all the way through the press, or bolt the support blocks to the lower support piece. Don't want to spit a steel shape out on anyone.
Even if the steel doesn't hit anyone, having all of the other pieces and a 20 ft I beam crashing around could be dangerous. I think with a little care and planning, it can be done fairly easily - if you have access to a press.
My inclination would be to bend it cold, but I'd have to research it. Maybe Tom can weigh in on heating 6061 Aluminum to bend it. He's way better at Material science (and most other stuff too).
Almost envy you - seems like a fun project!
... 14.5 deg doesn't seem so bad... might try bending it on my knee 