Just wanted to report on a recent cheap solution to making my treadmill more entertaining.
I bought the cheapest android tablet I could find that had hdmi output, a used
Hisense Sero 7 Lt), on ebay, for $40 including shipping, and a super cheap small flat screen tv.
The tablet sits on the treadmill book stand and the tv mounts to the wall behind the treadmill (under $100 used).
I can watch youtube, read the news, read comics, even browse the web.
Note1: This tablet gets bad reviews but has been working flawlessly for me and the price cannot be beat; if you have more advanced needs you might want to get a better tablet.
Note2: You will also need a mini or micro hdmi cable, and you may want to pick up a (usb) extension cord for the tablet power supply.
Note3: If your treadmill is loud, you may need to pay special attention to getting a tv with good volume (or use a soundbar).