Question about links on FACEBOOK - Driving me Insane

I have been looking everywhere and can't figure this out. So I figured I would ask here. Why is it that when I post a video link on my Facebook timeline, sometimes it displays as a small image with the link, and sometimes it is posted as a large image with the link. I've compared two different posts of mine. One that showed with a small Image and one that showed the large image. I can not for the life of me figure out the difference and how to make all the link images appear large. I am not uploading pictures. I used youtube video posts from my website for the test. Maybe its something with Facebook and not my posts? Any Ideas? Thanks!

Maybe it's because of the video resolution, Josh80. What you can do to make it uniform is take a screenshot of the video (whatever part of the video that you want to appear in the video thumbnail), edit it in pic monkey (you can resize, add texts, and do a lot of other stuff with pic monkey) or whatever tool you use to edit images, then upload the image on youtube.

well i never though of that. I do post stuffs via my fb page and i think i should check what you are telling here. Will update if i come up with anything like that

never tried with videos, but with images it is ussually related to de size, if the height is larger than the width, it ussually shows a small thumbnail

This doesn't seem to be an issue for most other pages. I see other pages where all their links post with the larger image. Maybe its something with the link structure or wordpress? Hmmm