Strange not experienced before fan sound!

I really am very new to macs, only had my MacBook Pro a couple of weeks but a loving it! Previously I used Windows for many years but will not be going back.
Up until last night I have never heard the fan at all on my MacBook. I watched a documentary on YouTube for about an hour last night and all was normal. I shut down my machine for an hour or so then rebooted to check out Facebook, I clicked on a short video someone had posted and as soon as it started to play I could hear the fan whirring very fast! It did so for the duration of the clip ( about 4 mins) also afterwards I noticed my MacBook had gotten warm underneath! Again I've not experienced any heat before. It seems strange the fan would run so quickly and create heat when watching a 4min video clip but not at all for the hour long documentary!
Any help will be appreciated

Dave

Not all videos are created equal. Everything to me sounds normal. The computer had to work a little harder…some heat got generated…and the fan kicked in to cool things off.

- Nick

Many thanks Nick, that's a weight off my mind

DaveLat said:

Many thanks Nick, that's a weight off my mind

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You're welcome. Don't stress about it. You have at least 12 months of Applecare. If you were truly having an issue…you would take it to Apple for analysis..and they would then do what needed to be done to make it right.

I'm sure as you use your MacBook or MacBook Pro (not sure which you have…these are two different model lines)...you will become more & more familiar with it's workings and behaviors under varying conditions.

- Nick

What probably WOULD have happened is that the fans would have kicked on if you'd left the machine alone after watching the long video (since that generates a lot of heat), but you shut it down before it could cool off properly, which slowed the cooling-off process down. I generally leave my MBP to cool off for some time after doing something really processor intensive like long video sessions or heavy gaming sessions, then put it to sleep (I almost never shut the machine down).

thanks again for the help/advice guys, great forum