2015 GMC Yukon Denali
The only "video" input that I'm aware of is the composite input (yellow port) on the back of the center console / RSE controls. It used to be with the pre-lightning Apple products (ex. iPhone 4 / the ones with the wide power connector), there was an adapter that went straight from the phone to the composite a/v input ports (red, white, yellow). However, this is no longer the case with Apple products that have lightning connectors. The connections are now digital. So, supposedly, I haven't tried this yet, but in theory you can get an Apple lightning to hdmi cable, then run it to a hdmi to composite adapter / converter box (requires power - some can draw from one of the USB ports back there), then to the composite input a/v ports). Talk about going from something easy with a single adapter cable to a total kludge of technowizardry. Keep in mind that even if you do get it to work, then, at best, you'll be watching videos at 480i.
In my opinion, this is not an Apple or any other vendors problem. This is solely on GM for a few reasons. 1) They didn't have a cohesive thought on, hey let's provide the ability to play HD/Blu-ray movies but not provide any compatible video inputs that can display at HD. 2) Composite video is a legacy technology. Most products I know of these days (at least the ones I buy) don't even have that option. At one point I thought about putting a Roku or AppleTV in there and then just use my phone or hot spot for data / connectivity from the device. But that was shot down after I test drove and bought the vehicle, and it wasn't a reason not to get the vehicle. 3) The excuse in that the development to production timeframe is so long that technology is obsolete by the time the vehicle goes into production is a joke. HDMI has been around a long time. I understand it comes with a royalty fee, but dang, pony up. We are all paying a premium on the new 2015s. The development team if they haven't already done so should already be including HDMI and planning for next gen technologies like 4K. Meaning they should already have plans for 4K screens via DP1.2 input(s). 4) Lack of innovation in this department. Let's be realistic. We are judging these vehicles more and more on their electronics capabilities and then how well they're executed (not just simply having a checkbox). We don't judge the rest of the vehicle like this: Do you have an engine? Check. Does it use a use gas? Check. Feature: Can it shut down cylinders to save fuel? Check. As we all know, each of those checks can vary widely between vehicles by the same manufacturer or different manufacturers. And if we're being honest, most of what we do in our vehicles (besides drive) is playing with, I mean using the features of, the included electronics. So quit trying to reinvent the wheel...put a stinking tablet in dash. It gives you voice recognition, maps, bluetooth, wifi hotspot, weather, pandora, spotify, it's more familiar and easier to use, etc etc. then just write custom apps or co-develop with the vendor. If doing this is not in the strategic plan, then innovate. Make a propriety system that is modular. Need new input ports, pay $200 for a new input interface module. Touchscreen seems ancient because technology y came out, pay 2k for a new in dash system. I know I know. It's so much more beneficial (profitable) for GM just have you upgrade the whole vehicle when the new model comes out with an hdmi port you've been wanting.
I see that they now offer units for the headrests that come with an hdmi input. So hey, when you spend $75k on a vehicle, what's another grand or two. Yea, not feeling it.
I've put this (lack of HD capable input ports) along with about 15 others into a feature request and sent it to GM. It'll take 10 years or so, but eventually you'll get what you need without buying the headrest accessories.
(Sorry about the long reply. I kind of got sidetracked.)