Videos show the wrong duration, sometimes, as well.
A couple of weeks ago, someone was asking for the full video of what looked like a 10s clip (which also played just 10s). Someone else replied, that it was literally the post. He got downvoted to hell (like below 100). He was right. After checking his comment, I went to the video and by seeking I got it to show the whole 2m and something.
This was not the first time this issue has appeared for me.
v.reddit.com is abysmal. I agree.