Youtube embeds sometimes failing to scale

I post a lot of videos on my blog.
I embed them with the youtube embed icon in the post area (comes with this theme)
Now sometimes for no apparent reason, one or more videos are suddenly twice their size while browsing the site (so you have a gigantic video on which you can only see 50% of it. (way too big for the post area)
Now my question is, how do I fix this?
My website = http://themavesite.com/wp/

Hi!
I can't detect the error. Could you give us a link to a specific page that displays the problem?

@Alice

Here's an example of what I got just now by going to my site
http://i.imgur.com/O2zKBl2.jpg

Hi!
As I can see this video works correct. Really difficult to understand your problem. Probably you you are using some third-party plugins that conflicts with our theme. You can try to disable them one by one to detect the problem or simply turn off "Load Content Dynamically". I attached the image where you can see that this post looks correct.

@Dave, the videos on the homepage now are working because I replaced them with the embed code from youtube itself.
But take a look at the archive page here:

http://themavesite.com/wp/category/videos/page/2