Hmm dunno about the video but well the DPS is really easy. Take weapon damage+any +damage on rings etc multiply by the APS + any IAS bonus (note you need to remove any IAS on weapon), multiply this by 1+ main stat % bonus you get your DPS with 0% crit lets call it NCDPS. To factor in Crit you its 1-% crit *NCDPS +(%crit*NCDPS*(1+crit bonus)) = your true dps.
As for passive skills these increase you DPS by X% compared to not having it.
As for errors I expect that a lot of that is due to rounding in the info displays.