In order to see those thumbnails you have to create them yourself. They're known as trick play mode or BIFs and are downloaded before the video starts to play. They're kind of a pain to create, but someone has posted a Python script that will use ffmpeg to create them. You can find it
here, but I haven't tried it myself.
However, the current channel doesn't support them although if you just downloaded the server it does support them. The next update of the channel will include support for BIFs or you can use raghu1111's modifications
here. You'd have to side-load the channel yourself.
You can see the exchange between raghu1111 and myself about BIFs on page 84 of this thread.
-JT
Roku Community Streaming Expert
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