I like Market7. I used this great, new tool several times in collaboration on some videos with our video production team. I myself am not a video production guru so I appreciated the ability to easily annotate specfic time intervals and areas of the video with "looks cool but formatting seems wacky" comments and not have to worry that our experts would not know what exactly I was talking about. And that is the key. There is little to no confusion (certainly less than usual) and I do not have to worry that my comments are duplicative so I am more apt to comment! I feel like my comments are valued.
For a great break down / business case on benefits, check out Market7's model in video: http://bit.ly/3BQJkO. A big fan of such clean models, I found this to be very interesting; clean tie between issues and resolutions, inputs, outputs, waterfall charts and fun images. Clearly Market7 is thinking about the ROI of collaboration from their product's perspective. That gives me confidence that upcoming features will continue to be value-add.