This is a very difficult question.
We already have most options.
Yep, that's the issue I am having. Lottery tickets contain pretty much everything with very few exceptions.
Voucher for immediate construction of a route.
Yeah, that's an idea that I had too and that sounds reasonable. Theoretically it could also be implemented in the track building process directly. Instead of giving you a voucher, you can simply complete the track by watching a video. The effect is pretty much the same, it would mostly depend on what is easier to develop.
But probably a bit too early think about the details here.
I suggest having a medal every day for watching 10 or 20 videos.
Maybe, yeah. Might not be super exciting for everyone (for example for me, personally, it would not be that interesting because I do not care at all about my personal prestige ranking), but definitely a good idea in general.
I would give priority to free lottery tickets.
This (and gold) would only be possible if we reduced the limit for videos massively (like a 3-10 videos per day). Otherwise this is simply waaaaaay too attractive and would essentially mean the financial end of RN, because even those players who spend money (and therfore allow the game to continue to exist) would reconsider if they really want to spend money on the game if they can have the same thing for free.
Supporting non-payers in some way is one thing and can (and should) be done to some extent, but essentially encouraging players to spend less than before is an entirely different topic and a luxury we definitely can't afford.