Long press on which item?
For the episodes I could reach it via the 3-dots.
Off informations:
Investigation 1: I tested the Google search. One downside here is that it opens always the browser first. Then you click on imdb link, which finally opens the IMDB app (if installed).
Using directly the imdb-search-link as mentioned in my previous post, the IMDB app would open immediate, w/o opening the browser at all.
Investigation 2: The API of TMDB or TheTVDB also allows to get the IMDB ID via their internal (eg TMDB-)ID. So it would be possible, if someone clicks on the IMDB-button for TV shows, that you grab the IMDB ID via their API call. This is not smart from coding side (API call + parse for IMDB ID every time), but yatse-users would get the IMDB button (like the one for movies, identical usage) 
Greetings
Eusi