I'll share with you some of what I've learned so far in my research on the oil expellers and my plans.
Yield: Most oil seeds contain between 35 and 45% oil. So for a 10 pound bag of seeds you would yield about 4 pounds of oil which somes to 51 ounces of oil for 10 pounds of seeds. That is assuming an excellent efficiency of oil removal which I do not believe can be achieved with a small manual press. I am planning, based on 900 calculations (that believe me no one wants to see, reads like a nightmare of confusion

) on being able to get about 38 ounces of oil from each 10 pounds of seeds. If I get more I'll have a party but I don't want to grossly over-estimate my yield.
The thing I haven't seen much on is that you should NOT waste the seed pulp left after extracting the oil. It can be used in cooking, baking, and with some of the seeds, just snacking. Many of the seeds are highly nutritious and you don't want to waste the nutrition left in the pulp. For an example I'll use Black Oil Sunflower Seeds. They are cheap, relatively easy to grow, the oil works well in cooking (with the exception of deep frying) and are currently eaten whole and as sunflower butter (similar to peanut butter.) Therefore, they are a highly usable seed pulp product.
Nutritionally, a one ounce serving of black oil sunflower seeds has 37% of the vitamin E you need, a host of the B-complex vitamins, and several needed minerals. Some of the vitamins will travel with the oil but the majority will be left in the seed pulp. There is also 5 grams of protein and 3 grams of fiber in each ounce. You could use it to make a version of "peanut" butter, you could use it in baking, adding it to muffins and whole grain breads, you could use it as a thickener in soups and stews. All of those would allow you to make valuable use of the nutrition of the seeds.
One of the complaints people have about nuts and seeds is the high calorie content. That is due to the oil in the seeds. A one ounce serving of black oil sunflower seeds has 166 calories - 120 of those are fat calories. So after you expel the oil you are left with a nutritious, low calorie food source.
Well, that's what I've found so far in my research other than collecting a bit of information on the how-to's which you have in your video. My next step is to get an expeller this summer (I hope) and put my plan into action. I planted a bunch of sunflowers as the beginning of my plan, if I don't get the expeller and get to make oil this year I can trade the dried blooms (with seeds) for eggs as chickens love to play with them and eat the seeds.
Please post and let us know if you get one and how you like it. I love learning from the other members here.