Fix: cutting long file names to avoid errors when saving

[Napuh]

Description

I've added a limit into the mp4 file name to avoid errors when saving files with very long filenames due to a long reddit post title.

Issue Fixes

This does not fix any issue I've seen in the repo but fixes a problem I've encountered when testing the code.

None

Checklist:

• [ x] I am pushing changes to the develop branch
• [ x] I am using the recommended development environment
• [ x] I have performed a self-review of my own code
• [ x] I have commented my code, particularly in hard-to-understand areas
• [ x] I have formatted and linted my code using python-black and pylint
• [ x] I have cleaned up unnecessary files
• [ x] My changes generate no new warnings
• [ x] My changes follow the existing code-style
• [ x] My changes are relevant to the project

Any other information (e.g how to test the changes)

In this particular post (https://www.reddit.com/r/explainlikeimfive/comments/vxwol7/eli5_in_light_of_everyone_losing_their_minds_over/) the filename generated is too long and throws an error when saving.
This modification to the name_normalize() method solves this.

[CordlessCoder]

One question: but why 70?
Almost all filesystems allow filenames with 255 characters, while some only allow 31

[Napuh]

Well, that´s an arbitrary number ngl. I figured out that 70 its enough to distinguish files.
If you think is better to change it to another number let me know.

[Darkatek7]

CHange it to 200 Please, doesn't work with 70. Always getting a filename to long error