Content warning: this is a pretty unpleasant video.
It was originally uploaded to YouTube in August last year, but has just started getting media attention again.
In the video's description, it says the child is 7 years old. BuzzFeed News has attempted to reach out to the video's uploader to find out more about its provenance.
It appears the child had been infected for several months. MailOnline has interviewed Dee Wright, founder of a chain of salons called Hairforce, which offer a specialised "lice assassins" service. Wright told the paper female headlice can lay 10 eggs a day during a 30-day lifespan, so infestations can be common.
Head lice can often give people an itchy scalp, which is caused by an allergy – but if you're not allergic, you may not notice they're there.