Oh I don't know ! So many kind of videos are possible
If I check on youtube there are maybe some ideas for you: -a tutorial af you're Harley Quinn makeup -"Harley Quinn voice test", to see us how you imitate her by voice^^ -the same thing with the all costume (maybe like "harleyxdquinn" she is quite famous to make small harley story in each videos) -a Q&A video to answer fan's questions) -videos to talk about everything !!
So here's some ideas where you could make videos. If you decided to make a youtube channel, tell me I'll be your best (french) fan ! For sure !