There is no 30-second skip button on the remote. In fact the buttons are so minimal there aren't even any good candidates for buttons to be replaced by a 30-second skip. The most glaring button ommission is that there is no aux or input button. Just about everybody with even a slightly advanced setup is going to need to use a universal remote as it stands now. When setting up my universal remote I used the codes for the rng200n and every button worked except for the thirty second skip. I tried the 30 second skip trick
from cnet and that worked on my older DVR with the dark silver remote but will not work at all with the X1. I also checked Remote Central and pretty much only found posts for other people looking for codes and info.
I ended up using a trick that I read about on the Comcast support boards. It allows you to customize the length of the skip on the page up button. So you can change it from 5 minutes to 30 seconds... or any time you want. Of course the downside is now I have lost the five minute skip. In my situation I'd rather have the thirty second skip than the five minute, plus the 4x FF is very fast so I use that for long skips.
the page up button (pg) is set by default to skip ahead 5 minutes. you can reprogram the box itself so that a page up command will instead skip ahead 30 seconds. from the xfinity xr2 remote, press "Exit" button 3 times, the press "0030".then try the xfinity xr2 remote, start playing a recording, press "pg up" button. it should now skip 30 seconds. you can then go into your harmony remote and customize your settings for the PVR. assign "PageUp" function to "Skip Forward" button.