Jim ... I haven't watched your video yet, but I can speak to your question without doing so.
The canister that you are refilling was made to contain a mixture of butane/propane at a given ratio. Straight propane requires a significantly higher confining pressure to be kept as a liquid, than does butane, or a butane/propane mix. However, that is only part of the issue, as a direct relation to the vapor pressure point at which the liquid in the can starts "boiling off" into a gas, is also related to the actual temperature that the liquid is being confined at in the can. The reason camp fuels have gone to adding a percentage of propane into their butane fuel canister, is that at temperatures near freezing butane no longer vaporizes, and so will stop feeding the flame in your lamp or stove. Propane operates, that is continues to vaporize, or boil off gas, to a much lower temperature, thus at any given temperature the propane is at a much higher pressure than is butane or a butane/propane mix.
Now here's where you can get into trouble with this. Propane canisters are typically built to a significantly greater strength than are butane and butane/propane mixed gas canisters, and for a good reason. They must be designed to safely contain the pressure of their contents in the hottest conditions that could reasonably be encountered, when the internal pressures will be the greatest, and propane is going to generate far greater pressures than the butane or a mixed fuel as the temperature rises. So you fill your mixed fuel canister with straight propane on a comfortable winters day, but leave that same canister in your automobile on a blistering summers day several months hence. That improper, under strength canister may just let go under such conditions, and then your car becomes a gas bomb. Not a pretty thought.
I believe it is my duty as a friend to point out this potentially serious problem, but I'll leave it to you to decide how you wish to proceed in this. For my money, I'd just use the proper gas in the proper canister and call it a day.
Now as disclaimer, I do refill my camping sized propane canisters from my 5 gallon tank, that I take to the gas station to refill. I do also use mixed butane/propane in a couple of my steam locomotives that have tanks that were originally intended for butane only. Problem with butane only in a small tank like my models have is that the absorption of heat by the liquid boiling off into gas inside the tank, rapidly cools the tank below where the pure liquid butane wants to vaporize, especially on cool winter days. By adding a little propane into the mix, typically 10-25%, it lowers the boiling point enough that gas still flows to the burner, even though frost may be forming on the outside of the tank, and being only a small admission of propane into the mix, it doesn't raise the tank pressure too significantly. I have checked with Accucraft on this, and they cautiously suggest that this is acceptable for the fuel tanks they put in their models, but also recommend only straight butane on really hot summer days when the fuel freezing problem doesn't exist anyway.
Hope this thumbnail of the issue is of help to you.