My stats were mediocre to be honest. I have a decent GPA but I did get B+ in some critical science courses and my GRE was not competitive (although I only sent it to Caltech and MIT)
At the end of the day what stood out can only be determined by the committee, but I would say it was my research experience that would have stood out and I think I effectively conveyed my passion for science through my PS. For the schools I cared most about, I also just made a sincere effort to get my name out there at conferences and such with faculty. I also skype interviewed several PIs at my top schools before applying.
YouTube would be fun, lol. I am just really grateful to have the opportunities I do and have the stellar mentors I have.