Program should detect FFmpeg if it's in the same folder

### Improvement Description
Program should detect if FFMPEG.exe is in the same folder as it and use that instead of asking for the full path every time.

### Functionality / Design
Detecting if FFMPEG.exe is in the same folder

### How to implement
maybe...
```
if exist ffmpeg.exe (
    set ffmpegPath=ffmpeg.exe
)
```