Is it illegal to use open source software as a part of your own software creation and resell it? For example, I am looking to create a software program that will convert videos and upload them to a video sharing site like youtube. I was looking at using ffmpeg as just a small portion of my product I want to sell, is this legal to do? What if i didn't sell the software as a bundle w/ ffmpeg, but sold my code separately and told the user they had to download ffmpeg in order for it to work? I'm assuming there wouldnt be a problem with youtube as long as each user entered their own API key?
I think your plan is fine. Its just like creating a software scripts that are dependent with JQuery. Jquery is an OpenSource but you can sell your script.
you can do that ... but its always better to confirm it again .. you can always sell what you have written e.g lots of people sell template for the open source scripts
its legal as long as you don't change the gpl and the gnu license stated there. wordpress is opensource but developers sell themes and thier codes. the only catch is they shouldn't change the licence.
nixproxy gave the right answer. You need to check the terms of the ffmpeg license. Some licenses, for example, would require you to release your software under the same open source license as the product you included in your software. Always go back to the original license and don't make any assumptions.