The default yaVDR 0.3.0a installation already includes the NoAd VDR add-on, but the add-on is not activated by default. The following command (re)runs the NoAd setup and enables you to activate the add-on:
# sudo dpkg-reconfigure vdr-addon-noad
# sudo restart vdr
From now on, the NoAd program will run for each new recording and will detect/mark the commercials.