According to the international intellectual property law and related laws, original works are protected by copyright once they are created, including limerick and video works. So your own limerick is posted on the website in the form of video, which can be protected by copyright.

However, in order to better protect your copyright, you can take the following measures:

1. copyright registration: According to the copyright laws and regulations of your country, you can take your works to copyright registration to further strengthen the protection of your works.

2. Clarify the right of signature: When publishing a work, make sure that your right of signature is correct, so as to ensure that others will not abuse or infringe your copyright.

3. Use watermark or digital signature: Add watermark or digital signature to your video works to prevent others from using your works without authorization.

4. Abide by the platform regulations: Before publishing the video on the website, carefully read and abide by the usage regulations and terms of service of the website to ensure that your works are protected by the copyright of the platform.

Sometimes, despite the above measures and copyright protection, you may still encounter infringement. If you find that someone has used your work without authorization, you can take appropriate measures to protect your copyright, such as negotiating with the infringer, sending a warning letter or seeking legal support.

Please note that if you use other people's material, music or images for video production, you need to obtain the authorization of the corresponding material or confirm its permission to use, so as to ensure that the copyright of others will not be infringed. If necessary, it is recommended to consult a professional legal institution or copyright expert to obtain legal advice according to your specific situation.