I see too many get this wrong and even the title of this video is in that basket. Multimode for short runs and best for local patching and connection. Commonly used by people going cheap and lazy. Singlemode for distance and throughput. Costs a tiny bit more but works way better.
The single mode fiber optical cable works good even the distance is short (1 foot). The cost is quite similar for both single mode and multimode. The single modes are mass deployed these days which has drive the cost down. It used to be expensive. Why multimode is common for local patching and connection? I think one of the reason is common practice. People will follow what have always been done. Another reason is the cost of the single SFP transceiver will be much expensive in 25G/40G/100G comparing to the single mode SFP. That is why the multimode is still popular for patching and the backbone network.
Physically connecting a multimode fiber to a single-mode Small Form-Factor Pluggable (SFP) module without any additional components is not recommended due to the differences in core sizes and transmission characteristics of these two types of fibers. Connecting multimode fiber directly to a single-mode SFP can result in significant signal loss, poor performance, and potential damage to the equipment.
Using a single-mode fiber with just one core means you're using a single strand of fiber to transmit data.is designed for long-distance transmission with a relatively narrow diameter, which allows the light to travel directly down the fiber, which results in higher transmission speeds and longer distances without significant signal loss. Not sure if I get your question right. If you're asking whether you can use a single core of a single-mode fiber for both transmitting and receiving data (bi-directional communication), the answer is yes. Just use a BiDi SFP module which allows bi-directional data transmission over a single fiber.
