Puzzle giveaway for artists and scientists [SOLUTION]

It's time to listen to some acid music! I'd recommend either this, or this. One of them leads to a headache, and the other one to a hidden giveaway (and potentially a headache too). However, only those of both art and science can find it.

You will find two English words, which together describe an activity people do in some video games (this should work as a confirmation you got it right -- if you get "qkrft aaeiz", you did something wrong). Use these words (all lowercase) to complete a bit.ly address. For example, if the words are "peel" and "potatoes", go to bit.ly/peelpotatoes.

The giveaway should end next Friday, at midnight CET. Oh, and for what game, you ask? It's what happens when you have a screwdriver, and then someone screws with zombies. Er, I meant, replaces screws with zombies.

(Disclaimer: although I am, technically speaking, a scientist, I got all my knowledge of this particular area of science from Wikipedia. So if the wiki articles I used were wrong, then you're zombied. I mean, screwed.)

EDIT: There's a typo in the music, because I'm a lousy pianist: to deal with it, you have to replace the first "L" that you decode with an "R". (In our example, you would have to use "peerpotatoes". Alternatively, use it as it is -- it's not an English word that way, but the address with "L" now works too. And remember, all lowercase.) Still, one person managed to solve it even without this clarification. ;-)

Please, if you are one of the cheaters from the infamous Serious Sam 3 giveaway trap, don't enter.

Solution:

Observations (things you should have noticed before even starting to guess anything):

• The code was supposed to consist of two words describing a gaming activity.
• The puzzle linked to two YouTube videos, one of which would lead to the giveaway. One of them is public and was uploaded last year, the other one was unlisted, uploaded around the time the giveaway started, and a short time after the start of the giveaway, an annotation was added to it, which made it totally clear that this video was the one linked to the giveaway.
• The audio track contained five groups of three notes, a short pause, and another five tone triplets.
• There were only three different notes in the whole track.
• (bonus observation for "artists"; if you don't possess absolute pitch, you had to deduce this from the other pieces of information) The notes were C, G and A.
• The video part consisted of a single frame of a spiral staircase.
• The videos were described as "acid" music. In the first video, it was apparently referring to the genre; in the other one, not.

Solution:

• The spiral shape of the staircase, "acid", and "scientist" hints lead to deoxyribonucleic acid, DNA. This is also supported by the fact that DNA consists of sequences of C, G, A and T bases. (Unfortunately, there is no "T" note.)
• Triplets of DNA bases are called codons, and each of them encodes one amino acid (again, the "acid" hint).
• Find a DNA codon table (for example here). Each amino acid has a corresponding letter.
• Write down the notes, find the amino acid for each of the triplets, and read their letters. Don't forget to perform the transcription (i.e. replace all C's with G's, G's with C's and A's with T's).
• (if you want, replace the first "L" with a "R" to avoid the error/typo; this was unnecessary, both the "wrong" and the "correct" address worked)
• Capture the flag: http://bit.ly/graspflags