As in many of these questions, context is everything. If you could provide that it would help all of us. First guess: Somebody made a statement about some subject that was not too important and didn't have a clear connection with what had been said before. It had gotten off the subject for no reason (random). By 'passing through' he was saying that it was of no importance. Things that pass through your town (other than a typhoon or such like) is generally of little importance to you.

oh, it means the person who gave the comment did not really intend to comment on your blog, post, or whatever it is you wrote (assuming it is you who wrote it). Probably that person was just surfing the net and came across your blog / post and he felt like giving a comment. Sometimes, we visit many blogs (bloghopping) and leave a comment in one or two posts. Then we can say we are just leaving a "random english comment" and we're "just passing through" Hope this helps!

This mean a non-english language video is viewed by an english-speaking user.You notice the word "ENGLISH" on a different language.It is common in youtube and kind of like an internet meme.Other people comment before me have never seen the video with "randon english comment passing through"in youtube.