No. Even if proprietary, you can find very detailed datasheets and guides to program most of those. Try finding a Broadcom SoC datasheet and you'll quickly understand what I mean. They're protected like nuclear launch codes.

There are many. The Raspberries are great value for the money as video players, also because of the really good CEC implementation, but for everything else, and I really mean everything else, there are much better powerful or cheap, sometimes both, alternatives.

Take a look at this list which is being updated roughly twice a year, and don't miss the downloadable spreadsheet comparison tables.

http://linuxgizmos.com/ringing-in-the-new-year-with-136-open...

Those however are the new entries; on manufacturers homepages there are "old" models that are still of interest today. Here are two examples.

https://www.hardkernel.com/shop/odroid-c2/

https://www.friendlyarm.com/index.php?route=product/product&...

From above

https://news.ycombinator.com/item?id=22438082