Read the attached link, and compare the photos and described symptoms with what you are seeing in your dogwood.  If none of those apply, the answer may well be our hot dry windy weather.  Give your dogwood a chance to come back stronger next spring before cutting it down.

https://apps.extension.umn.edu/garden/diagnose/plant/deciduous/dogwood/branchesdeadordying.html

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From close-up views of the remaining leaves on your dogwood, I don't spot any of the diseases mentioned in the Minnesota link n or in this one from the University of Pennsylvania.  Perhaps examining these leaves will allow you to spot one of the conditions.  If not, I suggest cutting down all dead branches, watching it carefully in the spring to see if new growth emerges, and giving it a second chance.

https://extension.psu.edu/dogwood-diseases

So, should I cut out all dead branches this Fall or now?  Some have a few leaves near the end of the branch and I assume I would leave those on the tree?  Thank you so much for your help.

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The best chance for this shrub/tree might be to cut it completely back to healthy growth now, rather than leaving long branches with a few leaves on top, hoping they fill out next year.  This way the water and nutrients can go to a limited amount of growth, hopefully resulting in a stronger plant next year.

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I'm sorry that I didn't receive your video.  If you'd like to have extra assurance that you're trimming your dogwood properly, you could contact a certified arborist.  For information on how to do that, see https://extension.umn.edu/planting-and-growing-guides/how-hire-tree-care-professional