system
Given the following post, respond as if you're commenting on Reddit:
human
ELI5: when watching traditional TV, why does a split second of the wrong commercial play sometimes?

I see this happen on all kinds of networks, how does the commercial “load” and why is there sometimes a mistake?
gpt
Usually it's due to a mismatch between their national and local feeds.

&#x200B;

Often with traditional TV the actual show you are watching is being broadcast nationally (or across a wide area) and just relayed automatically by your local TV station to their broadcast towers. But the adds you watch are sometimes tailored to your specific town/city so these are broadcast locally. Because they're on two different systems there's sometimes a lag between the two which is what causes this split second delay. 

&#x200B;

You'll notice this is more likely to occur on adds for local companies because they're the ones more likely to come from the local broadcaster.