O.k., time for your first homework!
1. find a way to make your dog run as fast as he can, tape him from the side and study his striding in slow motion or even frame by frame: how far apart his hind feet are, how far forward hind feet reach over front feet, how long and high the stride is, how his back look like and where his head is: many people think you want low head for running contacts, but in fact, you want the head look exactly the same as when running full speed in the fields 🙂
2. have a dog run over the plank, tape him from the side and compare it with the video above - you can tape it at an angle you're currently at. If you're just starting, restrain the dog before your plank, carpet or whatever you're using, throw a toy and release. Slowly bring the dog further away from the plank to really have them come to the plank with full speed. You don't need to overdo the distance, especially if you have long plank/carpet, as finding the plank could be problematic or the dog before you add some more height on it. Mark anything that looks like running in the fields from the first video, jackpot when feet are close to the end of a plank/carpet. Don't forget to click it or at least mark it with your voice! I prefer clicking, but you can also first use a voice and start clicking later, when you know your dog's stride better and can predict it better.
As we already discussed in comments before, we're for now throwing a toy in advance, letting the dog chase it, in order to get full speed. So yes, the dog is rewarded every time with a ball - so make sure that you really make the best tries even more special, use excitement in your voice, a play of tug on his favourite toy or food if that's his real preference - in short: make a party about the really good ones and don't worry about not so good ones - just throw that ball again! 🙂
3. to make it easier for the dog to understand what you're clicking for on that plank, we'll be teaching some tricks that are the best to help them understand how to use their feet and that you might be clicking them for using them. The two things you will try this time is cavaletti work - walking the dog over drawers or boxes on the floor - and teaching the dog to step with front feet on an object and clicking for any movements of hind feet: the final goal is a full circle in both directions, but first click even for just a weight shift and then go from there.
Post a video with all 3 assignments, first two also in slow motion please! This is a good check-up for those who are already running their dogs on a raised plank and a good stride-study that will help you see and mark the correct striding better for those just starting.
Also, read through the comments and see the videos in introduction page, you can learn a lot through videos and comments of others. Once you see your dog is running nicely, with an even stride, hind feet separation and hind feet reaching further from front feet (see discussion and video on that we had in comments!), you can put a brick or something under one end of the plank and have them run over slightly elevated plank - I'll tell you when you're ready based on the videos you'll send.
Left front foot just left the ground, hind feet reaching forward - this is what I mean by hind feet reaching over where the front feet were.
And this is what I mean by hind feet separation: hind feet hitting two different spots as far apart as possible (vs. staying parallel, hitting the same spot).