PHOTO:
The majority of photos are viewed on the internet and on screens. 5-8 Megapixel photos are all you need if you're viewing on a High Definition monitor.
'It's best to use a file that has double the resolution of the display in order to maximize the viewer's experience'.
So, if you are looking for the absolute best 4K quality on screen or plan to print photo enlargements, a 16 Megapixel or higher image file is recommended.
VIDEO:
Smooth, cinematic video is normally shot at a lower frame rate to maintain the motion blur in professional videos.
Fast action video needs to look extremely sharp and realistic and often is meant to be played back in slow motion which is why it is filmed at a higher frame rate.
Important!: Higher frame rate & higher quality image/video = Larger Files as well as the need for better lighting conditions and very fast lenses which cost thousands and thousands of dollars.