Very weird issue with embedded videos plugins

Buddies,
Something very weird is happenning to me. I’m developing a website which most of posts has at least one video. So until now I was just taking that well-known embedding codes given by YouTube and pasting into the posts.

Next step, looking for more flexibility, I tried to use some plugins for embedded videos. So, the problem: everything’s fine when I display one post, alone. However, when I call a list of posts (from a category, for example), videos disappear.

Again, the same problem happens with several plugins (Viper’s QuickTags, video.js HTML…, Pro Player), but not when I just use the embedding code provided by YouTube. And in listings only, when a single post is displayed it works fine.

Also, it’s not an excerpts issue, I’m using pretty normal, complete posts. Even on listings.

Well, I don’t know what to do to get some better visual to my embedded videos. Any suggestion? Thanks