Some background about the battle in the first vid.
The Siege of Deir ez-Zor:
A group of SAA ( Syrian Arab Army) and Syrian Air Force were surrounded by Islamic rebels in the city. Their defense area was centered by an airfield via which Syrian govt parachuted in supplies.
The siege lasted 3 years.
First it was Al nusrah and other Islamic militias but then ISIS/ISIL took over and continued the siege.
SAA: Syrian Arab Army (= Govt forces)
Al Nusrha : the most radical islamist rebels until ISIS came into being.
Free Syria Army : Western Supported rebels who fight Al-N, ISIS and SAA
SAA fights all other parties but has support of Hezbollah militias and Iranian Al-QUDS force (roughly could be called iranian Spec Ops) and has possession of the military hardware (tanks , planes Artillery) of the a national gov't. Low on men but for this reason much better equipped than other groups.
The first Vid shows the breaking of the siege by SAA after 3 years and the rescue of Syrian Army personnel from certain torture/death.
https://en.wikipedia.org/wiki/Siege_of_Deir_ez-Zor_(2014–17)