While we aren't sure what this means in terms of total viewers, we know that 20% of The CW viewers watch online and the 57% theoretically could be applied to total viewers as well. If that's the case, considering the final ratings were 1.56 million viewers, the approximate bump from both online and DVR is 2.75 million total. That's still good enough to be The CW's top show of the week (considering The Vampire Diaries finished it's season a week earlier).
The entire DVR chart for the week of May 14 - May 20th can be found at TV By The Numbers. I've updated our all seasons US ratings chart to include all of season seven's info now. The comparison from the first season is still quite interesting. I'll have to scientifically prove someday how the highest rated Supernatural season once DVR and online is worked in was very likely season four.
Okay, bring on season 8!