I suppose this question can be answered best by looking at your own viewers and video stats, do the shorter videos have more hits vs the long ones, vs the ratings. Who are your readers and why are they with you? Is it for your in-depth opinion and charismatic way or for facts and surface details.
For me though, quality is greater than content. So quicker, short, precise and in a way that the viewer can visualize your points (with graphs, cut-scenes etc) make the best reviews / overviews.
e.g. If you want to talk about 2 hours of Berlin opinions I would cut that video into almost a stop-time clip that flicks from user to user with the fastest edits you can do. Like if somebody asked you to squeeze ALL that into a 10 sec clip with a graph overlay that shows GREAT / UNDECIDED on first impressions.
An extended directors cut can be done after if you see a ton of interest in the shorter version. I also think summaries have more clickable value than seminars so I would do a summary / overview first, hope it spreads like wildfire then once you start getting bombarded with questions, do the biggie.
Just my personnel opinion.