I am thinking of creating a video library software which keep track of all my videos and keep track of videos that I already haven't watched and stats like this. The stats will be specific to each user using the software.
My question is, is python appropriate to create this software or do I need something like c++.
If you want your code to be REAL FAST, use C++ (or parallel fortran).
However in your application, 99% of the runtime isn't going to be in YOUR code, it's going to be in GUI libraries, OS calls, waiting for user interaction, calling libraries (written in C) to open video files and make thumbnails, that kind of stuff.
So using C++ will make your code 100 times faster, and your application will, as a result, be 1% faster, which is utterly useless. And if you write it in C++ you'll need months, whereas using Python you'll be finished much faster and have lots more fun.
Using C++ could even make it a lot slower, because in Python you can very easily build more scalable algorithms by using super powerful primitives like hashes, sets, generators, etc, try several algorithms in 5 minutes to see which one is the best, import a library which already does 90% of the work, etc.
Write it in Python.