How can I play a file created in OBS? I downloaded OBS based on an answer here.

I tested it by selecting "Start Recording" saying a few words, and then "Stop Recording"

I then selected File > Show Recordings, and it opened the This PC > Videos folder in Explorer; the file just created was there, named "2016-08-15 06-11-54.flv" 

However, 2-clicking it does not run it in OBS; it wants me to choose an app from the list to use, which, in my case, is "IrfanView" and "Look for an App in the Store"

I tried Irfanview, but the .flv file won't run because Irfanview is apparently lacking a needed Flash .DLL; Flash kind of gives me the fantods, so I let that slide.

Won't OBS play the videos it creates? If so, why doesn't it show up in the list of apps to execute the .flv file? How can I (if possible) get it to run the file?
OBS is a video streaming and recording software, not a video player. You will need either find a video player that will play an .flv file, or switch your settings in OBS to record to a different format, like .mp4, which most video players will be able to playback.