Thanks for all the responses. By overheating I mean it feels too warm and uncomfortable to touch at the bottom (below the ESC F1-F4 keys). I have the MBP 17" and it does not get this warm unless I am doing some heavy 3D rendering.
This is with the power adaptor unplugged by the way. I did not try the reset suggestion yet; would like to know if what I am experiencing is within the norm first.
Normally I would say no it should not get this warm. Although it's tough to judge one feeling versus another. I have gotten it very warm when plugged in and doing things like playing a movie compressed in mp4. I would suggest you downlod the istat pro widget, you can use it to monitor the internal sensors temperatures and fan speeds. You can then get a more objective another on whether it's the same as others.
Looks warm, but OK. Maybe hot but not overheating.
I think you will find the youtube video is what is driving up the heat. About the only thing that normally cracks up the fan on battery is compressed video (mp4, etc...) that I've noticed. Do all the other stuff you are doing without the youtube and you will see lower temps and the fan at 2500rpm. Start the youtube video and the fan will slowly start up as the temps climb.
Even so, the MBA runs much cooler to the touch than a MBP. Connect AC and run compressed videos on a MBP. Now that will get hot (burning) to the touch. The MBA is barely warm by comparison.
You are right about youtube causing excess heat... however, I noticed that even Aperture and iPhoto cause it heat up as well. Honestly, I find the heat uncomfortable to touch and don't think it is acceptable.
Well heat is certainly a subjective thing in terms of what is acceptable. I find the MBA runs much much cooler to the touch than any MacBook Pro model. I haven't tried a MacBook much but from what I remember I think it might be cooler than those also.
OK, so just color me an idiot! I'm in the US and do have it set to farhenheit. It never even occured to me. Thanks for pointing it out in a gentle way 😉 (shuffling off in embarassment...)
I am having this same problem. It is very uncomfortable to the touch and the fan 'whirs' quite loud. A good friend of mines mentioned something about 'too much thermal grease'. I think I am going to take it to the geniuses...