This FAQ applies to Nokia Lumia phones with 256 RAM memory (Lumia 505, 510 and 610).
Due amount of RAM memory, there are some limitations to streaming. It is quite normal that the media may pause playing at times, and then continues again. In some cases the media may not play at the highest quality available. This concerns all forms of streaming media, including music, videos, and podcasts. Media that is not compatible with your phone will not play.
Even with the smaller amount of memory, you can still enjoy a lot of video materials that has been encoded with less than 4 Mb/s, using H.264 v2 Encoder.