@jasonsf, this is a known issue with the server that has not been fixed in the last few updates.
The issue
Thanks for posting the log snippet. What is happening is Plex moves a file from the .grab folder into the final location with no problem, hence you can see it. When it goes to move the .ts file, it tries to place it in the following directory
/share/external/DEV3303_1/Share/Recordings/Shows/The Late Show With Stephen Colbert (2015)/Season 04/The Late Show With Stephen Colbert (2015) - S04E144 - Julia Louis-Dreyfus; Anna Chlumsky; Tony Hale; Reid Scott; Timothy Simons; Matt Walsh; Kevin Dunn; Gary Cocomskip.dictionary/
As you can see, your .dictionary FILE is the last folder in the path. However, that is NOT a directory, it is a file. So, Plex throws an error that it cannot move the .ts file into the directory, because it’s not a directory, it’s a file.
Questions
Are you running a post processing script of the Com Skip?
OR
Are you using the built-in commercial skipping option within the Plex server? Just some more info for the Plex devs if they ever decide to fix this bug.