Can’t say it is the case here, but often times launching a containerized missile involves the use of an low power expeller charge that propels the missile clear of the launcher. The purpose of the expeller charge is to provide a standoff distance to protect the crew and launcher from blast damage when the much more powerful main rocket motor kicks in.
If the main rocket motor doesn’t kick in, why get what the video recorded.
In the West, IIRC, these containerized missiles are what they call “certified rounds.” This means they have a shelf life during which they are supposed to be able to fire/operate without any special preparation. Basically, just attach them to the launcher and fire. However, there are usually servicing intervals where the missiles are to undergo inspection, adjustment, and testing (non-firing, obviously) to ensure they will still operate properly.
Sometimes older certified rounds are pulled from storage and fired specifically to determine whether or not the specified time frame between servicing is accurate. Of course, if this can be combined with unit training, it is a two fer situation; the missiles are expensive, so units don’t get to fire many of them for practice. Judging by how the soldiers are dressed, the casual vehicle positioning, the lack of any obvious special facilities, etc. I suspect this might be the case here; a regular air defense unit deployed out to a range somewhere to conduct live fire training.
Well, this will be an interesting entry in the after action report. Hope the transporter erector launcher (TEL) crew was alright.