I discovered my current phone can play Netflix videos without draining the battery heavily so I've started watching TV shows while doing cardio and find I can do 50 minutes or so easily now and the machine says anywhere from 400-500 calories burned per workout

Is it fine to do this every day with no rest days?

imagine yourself 10k years ago, in the place of your genetically identical ancestors.

how much time do you imagine they spent walking around or otherwise engaged in low intensity activity?

yes

just listen to your body

but it is amazing to do this every day

Perfectly fine if it's something like light jogging

Very salubrious for you... You can even go longer!

It's perfectly fine. And the benefits are not so much from the calories you burn while doing the cardio session. It's mostly from having better cardiovascular health and a faster metabolism which helps passively burn more calories throughout the day.

Passive metabolism doesn't occur, u only burn when you workout. Muscles burn a very small amount of calories passively even if you have put on extra 10kg. Gotta get pills to increase ur hr - fat burners and then u burn passively but also face health effects lol

good for cardiovascular health/metabolism? yes
good for joints? NO - thats why you dont do it 7x a week

he wasn't specifically asking about running.

Great for cardiovascular endurance

I personally would fear that much cardio would constantly put me in a deficit though and lose weight lol.