Wow dude
We got so happy about this, that I will personally find a way to do that for you
First i will ask the guys if there's a option but... there's a good thing. If you download only youtube videos. put them on one memory card, they will appear on the My Videos with no delete buttons so you will be safe. The only draw back is that the name of the video will be the youtube Hash, but the thumbnail will be there, (and your kid is 3 so please don;'t tell me that she reads already because I will know that she is a genius and is going to make her own canola before being 7yold ))) )

So my guide for you :

a. Select your download folders on the internet media settings (the memory card you will use for that, if there's more videos for her place them there)

b. download the youtube videos

c. Go to settings, media library and make sure the CARD (not any internal folder) is selected, the videos will be parsed and addded to the local video sections.

d. Refresh the media library!

Voila now you will need to convice her to use the MY VIDEOS
instead of youtube (I think the White icon will get more attention from her as she is used to that

Also another tip : as she will use the thumbs more than anyone else, you can start the playback from the my videos options and in the non-fullscreen playback hit options when there's a good screen to save it as thumbnail for the video to make it quite clear for her what video or kind it is... This will avoid any " black thumbnailed" video on the real videos.

Hope you like this,

And I am so HAPPY with the feedback if you (don't need to show her face only her hands) could videotap her using that we from the team would gladly accept this as the best payment ever )))))