The preferred solution (and the one I use) is to create default css outside of the media query breakpoints, and then this css will apply to e-ink devices (which don't support media queries -- even the amzn-mobi one, to my knowledge)
You should check the PDF of "Amazon Kindle Publishing Guidelines" on their website. Current version is 2015.4
I think your ...
By itself I don't think book trailers accomplish very much; they have to be coordinated with other publicity/marketing methods.
On the other hand, Amazon and Smashwords allow book trailers (with Amazon, you have to create an account on Author Central). So it gives potential readers a different kind of medium which can justify the purchase decision.
I have ...
Hi LaserYeti and welcome to the forum!
I personally don't agree with the usage of video for advertising a book. I think it is more logical to use the same type of media to advertise your product: Movies advertise with trailers and book advertise with written text like samples. For example making a website that promotes your work is not a bad idea! Also, ...
If you plan on advertising or promoting your book on Facebook and some other platforms, you will usually get a bigger reach with video than with an ad featuring a still photo, so that's one reason in favor.
I admit I am not into videos at all (ok, I made a video interview for the first book I wrote, but it was more fun than other), but I believe that having a chapter freely available should be a better publicity for the book. Of course, your mileage may vary: if you are good and brilliant in producing videos, and you like it, probably it will help sales.
I came up with something very close to what you have, see this thread:
The media query I have is:
kindle 1/kindle 2/kindle DX,
"other kindles" portrait,
"other kindles" landscape,