For little to no cost, you can use software that will convert your downloads to a format that is supported by your current equipment and then put that converted file onto the usb stick or the HD.
The other option is a media server (either software running on a specific computer on your network or a hardware box that is connected to your home network) that can then stream the various media files (movies, music etc) to any device that connects to it.
How to best go about addressing your request depends on how you wish to use the content you are placing on your storage devices. If you foresee a need or desire to lie in bed or next to the pool and stream a program to a laptop we'll need to incorporate network connectivity for all devices.
If you only wish to view this content on your main TV in the living room and do not need/want the content to be available for any other device, we can go another way.
My thinking at the moment is that you are attempting to address the issue of some file types not being supported by your TV directly. Even a new TV will not necessarily support all of the popular file formats that are being used to encode content these days. These protocols change and TV's generally do not update the codecs (software to display files on USD devices) very often if at all. You could buy a new TV and in a year or two find yourself back in the same situation you are in today or the new TV may still not play the files that you have today.
If I am correct in my assumptions and what you do now will meet your needs if the TV could just play the content that currently it doesn't understand, you can fix that with software for no cost other than time learning how to convert .mkv files to mp4 files for example. If you would prefer a more robust and scaleable solution that will store, show and backup your media content, we could go with a Network attached storage unit cost $400-$500. The other alternative is equipment similar to WD live media player either with network capabilities or without. Probably in the $50 - $250 range depending on capabilities.
Some hardware solutions are manufacturer supported and you can update their capabilities as your needs change or the codecs for your files change. Others are cheaper immediate solutions that will work now but may become less useful over time and require another solution at some point down the road.
Give it some thought and let me know what you think might work best for you. If you wish to just play what you download and do nothing else, I'd go with a software file format converting solution. If you think some more connectivity and capabilities are a good idea at this time, I'd then move on to the considering a media player box. If you want to store and make available to other devices your movies, pictures, music, backup and protect all of this content from accidental loss and put in place a solution that should last you forever, then we should consider a network attached storage option.
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