amp-video-iframe poster vs placeholder

Question

According to amp-video-iframe documentation the poster attribute is required: https://amp.dev/documentation/components/amp-video-iframe/?format=websites

But in the official example page: https://github.com/ampproject/amphtml/blob/master/examples/amp-video-iframe.html Google devs use a placeholder instead. Checking the tag validation source code, it seems that both use cases are valid: https://github.com/ampproject/amphtml/blob/master/extensions/amp-video-iframe/validator-amp-video-iframe.protoascii#L92

Does anyone know if the placeholder use case is allowed or it should be avoided? I cannot find additional information on the documentation

Answer 1

It is not required - that is a typo on the docs. Wether or not something is required is based on wether or not it is considered valid within AMP. The validator does not care if it is there or not, so it is not required.

source: work on AMP at Google