Unfortunately this will not always work. In fact a lot of vendors use proprietary streaming protocols that can not be viewed by standard players like VLC. Only via their own GUI or SDK.
- First and easiest approch is than to just ask the vendor
- Second you could use a network sniffer (like wireshark) to look at the traffic and identify the protocol this way.
By the way saving a part of a stream with the vendor specific player can be missleading as some vendors store a video in a different format than they use for streaming.