What fair use is, in plain words
Copyright gives creators control over their work. Some countries have exceptions, such as fair use in the United States or fair dealing elsewhere, that allow limited use for purposes like commentary, criticism, news or teaching.
These rules differ by country and are judged case by case. There is no magic number of seconds that makes a clip automatically safe.
Factors that are usually considered
Under United States fair use, courts look at the purpose of the use, the type of original work, how much was used, and the effect on the market for the original. Other countries use different tests.
In general, adding new meaning, such as analysis or critique, weighs more favourably than simply replaying someone's video with a few reactions.
Make your commentary genuinely add something
Show only the part you are discussing, pause to explain your point, and keep your own voice and face central. Your commentary should be the main reason to watch.
Credit the original creator clearly. Credit does not make a use fair by itself, but it is respectful and helps viewers find the source.
Platforms have their own rules
Even if a use might be fair under law, platforms can still remove content after a copyright complaint. Most have a process to dispute or counter-notify; read it carefully before using it.
For anything commercial, or if you receive a complaint, speak to a qualified legal professional in your country. Many creators also simply ask permission or use the platform's built-in duet or stitch features, which follow that platform's rules.
Frequently asked questions
Is using under a certain number of seconds always allowed?
No. There is no universal time limit; how much is reasonable depends on the work and the purpose. Short clips can still infringe.
Does my country have fair use?
Rules vary. Some countries have fair use, others have narrower exceptions such as fair dealing or specific quotation rights. Check local rules or ask a professional.