yup; Hanafi and the same with any salaah at all; more than two rakaahs are prayed in this way in two rakaahs salaah, one says all the recitations in the last sitting, i.e atahiyat, allahumma solliala, etc, but do you know that in 3 rakaat witr [which is wajib], on the thisd rakaah you have to read another surah too after faatihah, and then say Allahuakbar raising your hands upto ears again and then hold both hands on waist again and read dua e Qunut, or any dua would do such as the one said in last sitting position [allahumma inni zalamthu nafsi]
brother, Yes you're right, the video is showing only 2 rakat so that's why he's reading both atthiyato and durood sharief in the last rakat. If it was 4 rakat, then he would read only atthiyato in the 2nd rakat, stand up and then after sitting in the 4th rakat (or 3rd rakat if Maghrib or Witr), he would read atthiyato and durood sharief. As far as the dua after durood, that is optional and not obligatory to do so, and I guess that's why they didn't show it in that video, as they are just trying to cover the very basics of salat only. Insha'Allah your salat will be valid even if you choose not to read the dua after durood in the last rakat. For example, let's say you are making sunnahs in the masjid before the jamaat starts for any salat, and as you are reading atthiyat and durood in the last rakat, they start giving the iqamat, so now you don't really have time to read the dua after durood. In this case, you can leave out the dua after durood and just say salam after durood so you can go join the jamaat from the beginning. This is just one practical example, though you can leave it out at any time since it is not required. Also, the dua you quoted (Rabbana aatina...) is one of the several duas which can be read at the end of salah after durood. There are some others as well, and one has the option to read none, one, or even more than one if they choose. Insha'Allah it is virtuous to at least read one dua after durood (though absolutely not required to do so). The dua you quoted is also one of my favorites as it is very "thorough" and "complete", and it is very short and easy to memorize/read... in fact I believe it is called "the most complete dua" by scholars if I am not mistaken. Insha'Allah if we recite it often, in salah and outside of salah, Allah will accept it and we will have the best in this world and in the hereafer while being saved from the fire, INSHA'ALLAH. Ameen. I hope that makes sense. Allah knows best.