sources have passed this video, available here to CBRNe World. The source asserts that the men are in Aleppo and have recently found a stash of chemical defence equipment and detector.
The video does show a protective mask and canister and a chemical detector system. The mask and canister are russian design, with cyrillic lettering suggesting the GP-5 Russian respirator - or a copy of it. The respirator is very common and easily available through official route, or just bought from online surplus stores or ebay.
The detector appears to be an EntryRae from Rae systems a US company. The detector is not specifically for chemical weapon detection, primarily functioning as a four gas detector for entries to hazardous environmnets or scenes; it is is common use with fire and hazmat teams. It could be used to detect chemical agents though, specifically in a generic manner using the photo ionisation detector. It is also easily obtained, and this detector does appear to be in almost mint condition.
It is unusual that a US companies detector would be used by the Syrian Army for chemical weapons defence and detection, as one would more commonly expect to see other former Soviet equipment, which would be more suited to the job.