Jaudat, I'm going to assume you've got the relationship with the middle man under control and try focus on the question you asked, which is what kind of presentation to use for the meeting.
I think you're on the right track with the video followed by a more traditional pitch deck.
Both of these are useful tools in this situation. The video allows you to completely control the message and how it's delivered. This way if all else fails with the middle man, you've at least delivered that message across the line with the prospect.
The deck will give your representative a chance to put their own words and style to your message. This is beneficial as the middle man assumably has some level of influence with the prospects, otherwise you wouldn't have engaged him to do this job, right?
Finally, some more tactical points. I'd host the video and the deck on Google docs or some other cloud based location, and have him present live from there. As it usually goes these presentations are being finessed and evolved continuously, and you want your rep to have the latest and best version at his fingertips.
Secondly, while I agree with Zheng that eventually your rep will know just how to deliver a perfectly crafted mix of materials, in the beginning of this relationship I'd recommend tightly creating and controlling it yourself. Only provide 'creative license' once it's earned through experience with your product.
Finally, unless there are some time zone (or WiFi) restrictions around the meeting, consider making yourself available at the end of the presentation for some Q&A via video chat. This will allow you to gauge the prospect's reaction to the rep's presentation, answer some of the harder questions, and most importantly, give you a chance to show your rep how YOU sell the solution. Fastest way for him to learn the right way to do it.
Hope this helps, good luck!