Yea I was impressed by it but two of my housemates actually play drums and they said that most hip-hop beats can be played relatively easily on a set of drums
yep, quite simple as soon as you figure out the rhythm. Rap and Hip-Hop use pretty much to same principle as swing, jazz, and rock have (rhythmically that is, otherwise hiphop is just about dumbed down as you can get). They syncopate their rhythms. This means accenting what are normally the weak beats (up beats) and un-accenting what is usually accented (down beats).
The simplest of explanations (it will always be more elaborate) is in standard 4/4 time (4 beats per measure, and the quarter note is the main pulse) you would usually have
1 2
3 4. The underlined numbers being the accented beats. That is how it is for basically all classical, baroque, romantic, etc music. So count out 1 2 3 4 at an even pace while clapping or tapping, but accenting 1 and 3.
Syncopation however is accenting the offbeats/upbeats. So you'd have 1
2 3
4 . When you count the rhythm at the same pace as before, but now accent 2 and 4, you can feel/hear the difference. Syncopation is used so highly, especially in pop/hiphop/dance music, because it's better to dance to and more catchy.