I clean mine out every couple of months as not only would the heat cause problems, it could also catch fire if you were unlucky. A PC full of filth!
I run about 10 in an office with the server running 24/7 and they only get cleaned when they're upgraded; which is about every 3 years. Never caused me a problem. IMO, cleaning them out every 2 months seems a little OTT.
The cooler on my graphics card pics up a lot of dust so gets hot and spins the fan up faster making more noise. It drives me mad so I have no choice byut to clean it.
This is going to sound like bull - but it was certainly true in my first real job as a production engineer. If you leave dust on cooling fins it makes the surface area and therefore cooling surface larger - i.e. more surface area, more efficiency in disapating heat. I would also imagine using compressed air to ram dust in to fan bearings and slots on the mother board isn't a great idea. I suspect if dust was an issue - kit would have some form of filter - I have never seen any computer kit intended for general office use with filters, nor have I seen servers etc in computer rooms fitted with them either (and not all computer rooms and datacentres have filtered air believe me!) I don't think dust is such a big deal (though that PC in the vid looks like its been in a spray shop or similar!)
just cleaned a keyboard for the first time ever. Got to the stage when I had to crunch some keys down :-[
Not wishing to be rude but if you need to clean your pc fan that often you live in a dirty house buy a hoover. Mine only get a blow out job if I open them to upgrade