Has this hadith been authenticated by anyone other than Sheikh Al-Albani, and what is the opinion regarding it?

The number of takbirat (exclamations of 'Allahu Akbar') in the Eid prayers is seven in the first rak'ah (unit of prayer), in addition to the takbirat al-ihram (opening takbir), and five in the second, in addition to the takbirat al-qiyam (takbir for standing up). This is what the authentic hadiths indicate, and it is the view of the majority of scholars and Companions.

As for the conflicting hadiths, they are weak due to their contradiction with what is more authentic and reliable, and due to the weakness of some of their narrators. The musnad hadith (a hadith with a complete chain of narration) that the Muslims act upon is more worthy of being followed.

It has been authentically reported from Ibn Mas'ud (may Allah be pleased with him) that he used to say four takbirat in the first rak'ah and four in the second. The disagreement among the Salaf (early Muslims) on this issue indicates the breadth of the matter, and therefore, this disagreement should not be a cause for division and contention.