Hello & thanks for this nice forum. Together we are 130 years old. Because of some hills around we pimped our 24 gear MTB tandem with a rear hub. So we got plenty of electricity to use:
1.) Our stoker couldn't see what is infront happening. We mounted cheap Wlan Actioncam (50fps & some fur/foam over its microfone) at captains handlebar, and a smartphone as display at stokers handlebar. Therefore stoker can see whats infront & we have also nice tourvideos. :-)
I don't want to fiddle around with software programms. We copy those seperate 2GB SDCard (fat32) videos to a linux computer (ext3). And just by hitting a command into the shell it's combined into one big XXL GB file and ripped to 1/15 size (1280p) - using *****rger & ffmpeg. The big file is for screenshots (SM videoplayer) the ripped for pleasure & communication. Often we realize things first at the video.
2.) If you also have to use two smartphones (Apple & Android). It's nice to use both screens side by side at the Tandem. (One is glued at the flip cover of a phone. So either one can be "active" or both together.) Navi maps are different, they show different aspects. We use Komoot, Osmand+, Google Earth simuntaneously.
In good old times to carry a bicycle patch and a swiss pocket knife on tour made the deal. Now we carry three Smartphones on tour. Hmm? ... But, we really thought we would know our town. Now with a Tandem bike we explore it again! Incredible amazing how Navi maps & Google earth did push connected thinking. It's like sudoku for the brain.