Does anyone know how to get video uploaded and play in Hshow on Samsung Tab S 10.5

[sweetpie3]

I have created a Hshow presentation and stored it in Dropbox, however when I get to the slide that I want to show the video, I dont know how to insert the vid. Does anyone know how to do this? The video is already stored in the same folder in dropbox as the Hshow presentation. When I open up the Gallery, the beautiful preloaded videos that come with the Samsung Tablet are there but I can seem to get my video in there. What can I do?