I feel that this is absolutely third-party app territory. One that fills your needs well would be OPlayer HD (not a Universal Binary, iPad specific), chiefly due to it's capability to password protect content, with a few very notable caveats:
Put the 'safe for everyone' videos in iTunes, sync it and use the Videos player for those.
Use OPlayer's sync mechanisms (iTunes Document Sync, WiFi Transfer, etc.) for getting the restricted videos into the app, and then password protect it.
First, note that OPlayer does not support a simple pin/passcode, instead you have a full keyboard to type out a password. (You can always make your password a simple pin, I'm just stating that the input interface uses the full keyboard and not a "ten key" digit mode.)
Second, note that OPlayer's password protects the WHOLE app. Not just specific videos. This is why I suggest you split up the videos between the built-in player/iTunes housed videos, and OPlayer specifically.
Lastly, and perhaps most annoyingly, if you are done using OPlayer you should absolutely double-tap the home button and manually close OPlayer when you're done with it. If the app is running at all, even "suspended", you will NOT be re-prompted for the password when you return to the app.
I would simply say that your Library is corrupt for some reason. As your library is a virtual reference lookup to your actual music files, if it has a problem it is possible that it will either give you issues at program startup or perhaps when you add something to your library as it will read the reference file and encounter issues when trying to add to it.
I first of all tried all the obvious, Disk Utility
repair, permissions, deleted and reloaded iTunes, etc. However all of that will still use the original Library file so it won't solve the issues so many are having with iTunes.
The simplest yet time related route is to rebuild your library. What this means is that you need to create a new one, and import all your content again. It may take you 30 minutes and for your computer 10 hours.
As it's your library that's corrupt and not the actual files/file structure that is the problem you will be able to import all of your music again together. About 95% of your albums will be kept together although in some occasions with downloaded albums their reference name will not match that of the official release so it may be separated and in need of the artwork but neither is a big take to sort out. It's the same deal with your movies.
- Quit iTunes
- Hold Alt and click iTunes again
- Select new Library (don't worry your old one is still there and will not be deleted)
- Then you can start to rebuild. You can always go back to your old Library by closing iTunes, holding Alt and clicking on iTunes.
To select which library to open - you will see that in your Music/Itunes folder there are now two libraries and the xml library file is in the sub folder for each for you to select if you cant find it. Give yours a simple name when you create it such as 'ITunes Library 2' that way you can search for it too if you can't find it.
The only issue with this method is having to backup your iPhone/iPad or other device in your old Library as it can only be sync'd with one library. However, once you are happy with your new library you can Erase your device and sync it with your new Library.
When you erase your iPhone for example, it will only wipe/erase the content (Music, Movies, etc.) it will not delete Apps, Messages, Bookmarks, Photos, etc.
I hope this helps, as it not only sorted my iTunes issues for good but also made my iMac a lot faster in general as iTunes is not struggling and does not crash any more.
Best Answer
I would assume that this is possible using AppleScript, and when it comes to AppleScript and iTunes, DougScripts.com is always the place that I check first, which led me to this:
Skip Back or Ahead: https://dougscripts.com/itunes/scripts/ss.php?sp=skipbackorahead
I don't know if his scripts control video as well as audio, but if they don't, I bet he'd know how to adapt it.