can I use FFmpeg.exe video recording feature for commercial use? ffmpeg.exe
As the project itself says, "FFmpeg License and Legal Considerations ... are a constant source of questions and confusion". They go on to note that
FFmpeg is licensed under the GNU Lesser General Public License (LGPL) version 2.1 or later. However, FFmpeg incorporates several optional parts and optimizations that are covered by the GNU General Public License (GPL) version 2 or later. If those parts get used the GPL applies to all of FFmpeg.
If you are simply bundling the executable alongside your program, and your program invokes ffmpeg through userspace, you likely aren't making a derivative work, so you need only honour the licence terms on ffmpeg with respect to ffmpeg. If you are making a derivative work of ffmpeg, for example by linking your application to it, things are more complex.
If you trigger the GPL, your commercial application will have to give all users the four freedoms, which is likely to make it non-viable as a commercial application. If you can keep your software to being a derivative of ffmpeg-under-LGPL, then you will only need to distribute the source of ffmpeg, and not free up your application.
The project's page lists the things the project thinks you must do in order to keep ffmpeg under LGPL, which list starts with (but is not limited to)
Compile FFmpeg without "--enable-gpl" and without "--enable-nonfree".
Use dynamic linking (on windows, this means linking to dlls) for linking with FFmpeg libraries.
Distribute the source code of FFmpeg, no matter if you modified it or not.
If you follow all their advice, it is likely that you can use ffmpeg in your derivative work without having to free the whole work. Note also that on the subject of patents the project adds
There have been cases where companies have used FFmpeg in their products. These companies found out that once you start trying to make money from patented technologies, the owners of the patents will come after their licensing fees. Notably, MPEG LA is vigilant and diligent about collecting for MPEG-related technologies.
As ever, IANAL/IANYL, so you should get proper legal advice before relying on it.