15 minutes sounds decent enough, but 5 minutes is way too short. Most boss fights last a lot longer than 5 minutes. However, this feature will live or die based on the post recording options of each console:
- Will I be able to upload and view them on YouTube, twitch or any other service? Or just one service owned by MS or Sony?
- Will I be able to include voice-over? After effects? Concatenate different videos?
- Are there any editing tool incorporated in the console? If not, is it possible to copy the raw video to a USB drive to edit it on my PC? Is it going to use some proprietary codec or watermark?
I don't think that feature will pull me one way or another about my decision. Regardless of my choice, most likely I will try recording 1 or 2 videos before forgetting that feature even exists... However, the first company that can give a proper answer to those questions will make the difference between those that designed the feature since the beginning, and those who think of it as an afterthought.