Someone posted a defamatory video about my business on YouTube causing me loss of customers, can I sue them?

Yes, online defamation is punishable under Section 499 and 500 of the Indian Penal Code with up to two years imprisonment and fine, and under Section 67 of the Information Technology Act, 2000 for publishing obscene or defamatory content in electronic form. You can file a civil suit for defamation claiming damages for the financial loss suffered, as well as a criminal complaint before the Magistrate. First, report the video to YouTube through their defamation reporting tool and send a legal notice to the uploader demanding removal and an apology. Preserve the video URL, screenshots, viewer count, comments, and any evidence of lost business like cancelled orders. File an FIR at the cyber crime cell if the uploader is identifiable, and the court can direct YouTube to take down the video pending trial.