VOD Pull vs HTTP Pull (pseudo-streaming)
1) HTTP Pull with Pseudo works with specialized flash players that support pseudo-streaming. It also works with Apple and Android, using progressive downloading (byte-range seeking).
2) VOD Pull works with practically any flash players over RTMP, and specialized flash clients require HDS (HTTP Dynamic Streaming). It works with Apple and Android, using Apple on HTTP or Android on RTSP.
However, to differentiate them, VOD Pull is more efficient comparing to HTTP Pull Pseudostreaming:
a) The Pull from Origin to Edge server - Wowza's caching module only requests the chunks that are requested by the client. On the other hand, Nginx will download everything from the beginning.
b) Because of (a), the scrubbing is slow when a video file is not available in Nginx cache.
c) RTMP and RTSP use a single connection, so scrubbing is very fast, comparing to Pseudostreaming which has to establish a new HTTP connection when scrubbing.
d) RTMP only buffers a fixed amount of data, determined by the flash player. Pseudostreaming will be as fast as the visitor's port speed.
The downside of RTMP though is that flash doesn't buffer the video to the client's disk. Therefore if you replay a video, it will be downloaded again.