I just came up against this same issue and have used the following fix.
PLEASE NOTE: This involves a very simple edit to the plugin file itself ‘video-poster.php’ which means that should you update the plugin in future then this change will be overwritten and you’ll have to redo it. I’m not sure that’s a big issue in this scenario as the plugin has not been updated in almost and no longer appears to have an author page outside of www.remarpro.com but I thought I’d mention it upfront in case you are working on a client site and you don’t want to risk the possibility of them overwriting it with an update in future. Maybe there is someone out there who can suggest a way to implement the same change outside of the plugin file but that’s a little beyond me right now …phew, boring bit over – onto the fix.
So open up video-poster.php in the Simple Video Embedder plugin folder and scroll down to line 143 where you will find the follow function…
add_meta_box("p75-video-posting", "Post Video Options", "p75_videoPosting", "post", "advanced");
this is responsible for adding the various video related fields to your post admin screen. The 5th argument passed to the function (“post”) is the part that dictates which post-type you are adding this too. So if you want also add the videos to your pages too, then you just need to make a new line below and duplicate this whole function there and edit the “post” argument on this new line to “page” instead…
add_meta_box("p75-video-posting", "Post Video Options", "p75_videoPosting", "post", "advanced");
add_meta_box("p75-video-posting", "Post Video Options", "p75_videoPosting", "page", "advanced");
make sure all of this is still inside the curly brackets belonging to the ‘if( function_exists(“add_meta_box”) )’ statement above.
I haven’t checked this personally but if you want to add the functionality to a custom post-type then it should just be a case of creating a new line with the same code above and substituting “post” for the name of your custom post-type instead.
Hope that all makes sense.