if you have downloaded app trailers before, you can go under your purchase history and find it. it will let you redownload it from there. otherwise, you can find an ipa file of it online and install it to your device from your computer using itunes iirc
As long as you arent running stoves to do it you won't get banned. Although if you're converting to perk points, I recommend you do the manual video watching in perk wallet. I can earn like 4 points a minute doing this non stop