I completely understand that concern and it is one we're very much focused on making sure doesn't happen. The average weddingmixer gets over 500 photos and videos in their project. The reality is couple's usually end up with so much content they are amazed. After 6000+ couples, we have had only a handful (less than 10) who didn't have enough video to work with (mostly because someone left the cameras in the hotel or at home) and we were able to still create beautiful slideshows.
People will be taking photos and videos on their phones and cameras naturally and with just a little bit of prep and encouragement, you'll get even more. After reserving, we provide a lot of tips, suggestions, email templates, instructions, etc, to help your guests. We also suggest not asking 1 person (unless they love being the video person) to spend the whole wedding acting as a videographer. Rather, ask a few different people to capture certain moments - getting ready, in the limo, ceremony, speeches - and then pass the camera to the next person. At the reception the cameras get passed around on their own and you get some of the best 'behind the scenes' moments.
We'd be happy to hop on a call and answer any other questions as well as things to look out for and ask from videographers if you decide that is your best option. We truly want to make sure everyone gets the right wedding video for them. https://calendly.com/weddingmix