You really shouldn't mix frame rates. Temporal stuff is a bitch. Intelligent frame interpolation does cause a tax to the processing time. So if there is not processing time hit, it makes me think it's throwing out frames or just quickly blending them. Not that I've noticed.
I can't control what Youtube does to the video after I upload it, Youtube always transcodes it.
Sorry if I mentioned this before (?) but if you're looking for a relatively cheap online back up method, you might get a Vimeo pro account. Yea, not as a way to distribute, just as a second, third or forth back up. I use it to upload 1080p content, and the nice thing is (I think you have to have a pro account for this) is that yes, they transcode your video for playback, but they give you a link to the original uploaded video for free(no compression - same as your upload). It's kinda win/win assuming you're not pinching pennies to pay for it. ($17 a month - blah - cheap as chips!)
Reason being - I'm not sure if you've been following the horror stories of some you-tubers that have their account deleted - or put on probation. One guy recently had a two year old video flagged for "Community Guideline Strike", and with some of your rants about religion and kickstarter projects(batterizer/solar roadways), it could easily happen to you by some hater(s). All it would take is X number of complaints and you're screwed.
This guy got his wrist slapped by ebay by just a few complaints for "hate speech" but they banished him from uploading videos longer then 15 mins - and missed out on a lot of money. Scary stuff if you're making a living on youtube. You might want to watch this:
WARNING - lots of cussing in the video