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Roku lays off 300 workers and removes streaming content to save money
(www.engadget.com)
This is a most excellent place for technology news and articles.
The buffers on streaming devices are much smaller on these devices because of how cost reduced they are. You're way overselling how large they are.
Also, 80mbps is actually a pretty common avg bitrate on 4kuhd blurays. You have 100gb of disk to play with and they generally want to use it as much as possible.