[TheRealPomax]

There is so much value in doing this in a normal application with a UI that lets you see what you're doing. ffmpeg is a fantastic utility if you already know what you need, but it's absolutely terrible for jobs where you need to be able to see and do things between the two states of "having input" and "having final output".

[syl_sau]

I agree, although it has to be noted that that you can preview most ffmpeg commands using ffplay. The syntax is the same as the ffmpeg command, without the final output filename obviously.

[TheRealPomax]

Right, but now we're going "replace this single app with a normal graphical interface for working with visual media with multiple command line utilities including the terminal that you're always going to have to look up the commands flags for" and that's not really selling it =P

[llampx]

Ffmpeg is a great tool for programmatically editing videos. For one-off jobs a gui editor is probably better.

If you want to create a slideshow for 300 folders of images, ffmpeg is really your best friend. For one, maybe use a gui editor.