CMOS Battery is a laptop type cable assembly with battery. It is found on the side of the motherboard that is under the fan.
It appears to be a 2015 model. CMOS batteries in a proper design last 6 to 10 years. The Revo RL85 is closer to a laptop missing parts than a desktop PC. Laptop CPU and graphics processors, laptop wifi and internal antenna, single stick of laptop ram, external brick power supply, seems to have slots for up to 3x laptop memory storage SSD or HDD of 2.5 inch drives.
At 6:06 of the video, look for the black and red twisted cable connected to the white connector on the motherboard:
Acer went cheap with the CMOS battery brand as KTS (Lixing / Vic-Dawn Enterprise Co., Ltd.) in a CR2016 battery on a cable that is soldered and sealed and generally replaced as a cable assembly. Panasonic brand ones are superior, but may be a different connector. You can hack your own replacement CR2016 battery,but they can explode with heat.
It probably will not fit the the more standard thicker CR2032 size.
The battery cable assembly is known as a KTS 491 CR2016W
The battery is a coin type 3V, 90mAh. I think the 491 represents the connector and wire length rather than a date code.
KTS brand CR2016 appears to be only 83mAh
Unfortunately, extensive internet searching did not find the exact replacement and it is uncertain which similar units can be used.
It is definitely a 2 wire.