Helmet and handlebar action cameras and rear-facing safety cameras.
Cameras on an e-bike fall into two jobs. Action cameras capture the ride for fun, and safety cameras record traffic behind and ahead of you in case something goes wrong. Commuters on roads like Dallas Parkway frontage or Preston Road increasingly run a rear-facing camera that doubles as a taillight, with loop recording that overwrites itself until you need a clip. Both kinds need to handle the same things: vibration at 20-plus mph, rain, and the limited real estate on a bar that already holds a display and a throttle.
Mounting is the first decision. Handlebar mounts are simple but get the most vibration; a stem or out-front mount with a stiff arm is steadier. Helmet mounts follow your head and give a natural view but add weight to the helmet and can affect how it sits. Seatpost mounts for rear cameras work well unless a rack, bag or fender blocks the view, in which case a rack-mounted camera-light is the answer. For any mount, the e-bike buzz that loosens phone mounts loosens camera mounts too, so check clamps and use the tether.
For safety recording, prioritize loop recording, automatic start, enough battery for your round trip, and a wide, reasonably sharp view that can read a license plate in daylight. Resolution matters less than stabilization and low-light performance for a commute that often happens at dawn or dusk. For action use, electronic stabilization and a wide field of view make hub-motor bikes look smooth on camera even when they are not.