Whether or not it is allowed/correct depends on the context. By itself, you would be well advised to not use this construction in a regular conversation, since it is wrong/odd.
There are examples however, where this phrase is correct. For example in old Japanese, が and の were used interchangeably, so it can be correct in a historic context.
Most commonly, this construction is used as an abbreviation if it's clear from the context who or what the sentence is about (耳の大きい+[omitted noun]). You mentioned that you encountered this phrase in a YouTube video, so I think it's likely that it refers to something mentioned in that video (I guess something with ears?!).
A typical example would be, that the speaker made a statement about a person/animal, then realized that he/she forgot to mention an important piece of information (the big ears) and then immediatly adds this abbreviated sentence to leave it up to the listener to figure out the correct meaning and grammar.