depends what you are posting. if you are posting a nice picture slide show to a song, thats seems to be fine.
it’s the flip side of the coin that can ruin shidduchim. if it a video of bnei/bnos yisroel doing something inappropriate, then why are they putting it on in the first place? personally, i have an extreme dislike to the youtube videos of yeshiva bachrim spoofing jewish songs and making fools of themselves. they dont have to sit and learn 24/7 but there is no reason to shout to the world that you are in yeshiva and this is what you do.