It seems he said "tailadot" not "at hyielidot" ... is it a rule to combine them or it is normal.
et ha yəladot -> et hayəladot -> et hayladot -> etʰayladot -> etayladot -> tayladot (Copied and added to from Panglossa below)
In fast, casual speech, this reduction tends to happen. It's similar to in English when "it is" becomes "it's", and "they are" becomes "they're". In writing, we can represent casual pronunciation as 'ת, so here it would be הפיל רואה ת'ילדות. However, this is very slangy.
Thank you. Even looking at the correct answer I hadn't been able to match the speech to the words. Now I can. Previously the only word I could think of that might match the speech was "תרנגולת"
It's no "at hayeladot" — it's "et". "at" is the feminine form of "you" and "at" (the a is pronouned ah) comes before a definite direct object.
All words in every language are "joined". There's nothing that physically separates words in speech, so only as you become familiar with a language can you start to figure out where the boundaries between words are. If I play you a recording of a language that you've never heard before, you won't be able to say where one word begins and ends, it is just a string of syllables.
Particularly if it is spoken much quicker than a beginner can understand it.
What about: The elephant is seeing the girls? This was flagged as wrong when I typed it.