These days, when watching social media or YouTube, there are many times when you wonder, "Is this really a person? Or is it AI?"

The faces look natural, and the voices sound almost like real people, making it confusing.

I have looked into how to distinguish whether a video is made by AI or not.

The first thing to look at is 'eye movement.' Videos made by AI often have unnatural blinking or blink at regular intervals.

Sometimes they don't blink at all, or conversely, they blink too frequently.

If the gaze is slightly off or feels out of focus, it is likely an AI video.

The second is 'lip movement and pronunciation sync.' AI videos often have lips that do not match the sound perfectly, or the pronunciation sounds blurry.

Especially in languages like English, where pronunciation changes according to lip shape, awkwardness is more pronounced.

The third is 'skin texture and light reflection.' AI videos tend to look overly smooth, or the skin appears plastic-like.

Real people have subtle blemishes, wrinkles, sweat, and changes in shadow on their faces, but AI cannot perfectly express those fine differences.

If the direction of the light hitting the face is strange, or if the shadows around the ears or neck change unevenly, it is likely an AI video.

The fourth is 'hands and movement.' AI still struggles to perfectly replicate finger movements or the shape of hands.

So fingers may look unnatural, or they may suddenly disappear and reappear.

Also, when holding objects, hands may slightly overlap, or gestures may often appear robotic.

The fifth is 'background and shadows.' If the background looks too awkward, you can suspect it was made by AI.

The sixth is 'voice.' AI voices may initially sound like real people, but the intonation or breathing at the end is unnatural.

Humans breathe while speaking or mix subtle emotions in the middle of words, but AI speaks in a consistent tone.

Especially, conversations with emotions or laughter often sound awkward. Finally, there is also a method of checking 'metadata and tool traces.'

If you download the file and check the properties, traces like the name of the production tool may remain. Nowadays, this information can be deleted, but it is difficult to hide it completely.

In summary, AI videos may look perfect, but there are always parts that are 'too perfect to be strange.'

When you look at the focus of the eyes, lip shape, skin texture, hand movements, lighting, and voice all at once, at some point, you get the feeling that 'something subtly doesn't seem human.'

In the future, there is a high possibility of legal requirements to include watermarks on AI-generated videos, and some regions are preparing regulations. However, there are many technical and policy obstacles to actual implementation and execution, and it is still difficult to say that a completely consistent system has been established.