The sl300i (the same holds for the sl400i) has quite some issues regarding video playback. Videos with high bit rates (often the case) won't play smoothly and shutter. The successor the slm5500 has no problems with high bit rates but has other issues such as: it is not recognized by the 9800i, doesn't play srt subtitles and won't stream the correct ac3 stream through the coax (only stereo PCM signal) see the www.streamiumcafe.com
forum for an extensive overview of the issues.
There are many stations which won't have the issues, for example media streamers build around the sigma chipsets. Also be aware that the remote 9800i still has issues which unfortunately aren't fixed yet and probably won't be fixed in the future. There hasn't been a firmware upgrade since we (the users) reported them.