This is part of series I'll be developing (over time) on Adobe Lightroom glitches and how to solve them. It is intended for members of The Photo Managers who are looking for answers when Lightroom is acting weird. Most of the answers come from the Adobe forums but some I've just figured out by trial and error. This particular answer has been taken and adapted from a forum post. (Search: Lightroom Dynamic Link Server error in the Adobe communities find the original thread.)
I'm starting with this error message that I've sometimes received when trying to import videos. I can't say this is THE solution as I've no idea if this will work every time and everybody, but once discovered I have found this to work for me.
You receive a 'Dynamic Link Server' error message when importing videos OR
You can see your videos in your Lightroom catalog but they simply won't play OR
You can see your videos in the grid and see the movie playing when you scrub your mouse over the thumbnail, but the video won't play when you enlarge it.
Make sure your catalog, if not your entire computer is backed up as ... you never know. Skip this step at your peril.
In Task Manager (Windows) or Activity monitor (Mac) poke around for 'Dynamic Link Server'. It will probably show significant CPU and memory usage.
Select this task and look in the menu to find how to quit or kill the task. At the time of writing it is under View/Quit Process on the Mac.
When you reopen Lightroom all should now be right with your video world.
I hope this completely unintuitive solution to a singularly unhelpful error message (are you listening Adobe?) works for you :)
P.S. If this doesn't work. I've seen that deleting/reinstalling the VLC media player seems to have been 'the fix' for several users - so if you have this particular player maybe give that a try.