No, this video does not depict a neo-nazi leader dying in the middle of a speech. Namely,
- Yes, Petro Vushko died at age of 91 during his speech at the monument to Shukhevych;
- No, he was not a leader of OUN/UPA;
- No, he was not a nazi or neo-nazi.
The event took place on 9 July 2017 (source, translation).
The head of the OUN-UPA Brotherhood died during a speech in front of the monument to Shukhevych
During the patriotic speech near the monument to Roman Shukhevych, in front of a large community, the head of the Yavoriv regional OUN-UPA fraternity lost consciousness and fainted. After the attempt of the local doctors to [resuscitate] bring him back to life, under the prayers of Fr. Taras, without regaining consciousness, at the age of 91 his heart stopped beating - Petro Ivanovych Vushko.
Petro Vushko was born on June 18, 1926 in the village of Kobylnytsia Voloska of the former Jaworów County, now Poland. He was raised in a patriotic family. During the German occupation, Petro Vushko studied at the Ukrainian State Trade School in Yavoriv. In 1944 he became a member of the OUN under the pseudonym "Orlyk". After the brutal investigation, Petro Vushko was sentenced by a [Russian] tribunal to death, which was commuted to 25 years in [Russian Gulag] concentration camps and 5 years of deprivation of civil rights.
He headed the Yavoriv District Brotherhood of the OUN-UPA, the Yavoriv District Union of Political Prisoners, a member of the regional branch of veterans, a member of the commission for the restoration of the rights of rehabilitated Yavoriv District Council, and took an active part in all patriotic events.
More sources from Ukrainian regional and national media:
- The leader of the OUN-UPA district fraternity died in Lviv region during a speech in honor of Shukhevych — TSN
- Petro Vushko, an activist of the Lviv Regional Union of Political Prisoners of Ukraine, has died — Forpost Lviv
From the articles published in the news outlets, we can conclude that:
There is no information of whether Petro Vushko was a leader of UPA:
- At the time of UPA activity, he joined the partisan movement in 1944, just around the time when the Russian occupants recaptured Ukraine (28 October 1944). It seems doubtful that Vushko could get a leading position in a very short period of time.
- In modern times, he led the Yavoriv regional Unions of Veterans, Political Prisoners and the local Brotherhood of the OUN-UPA which has mostly ceremonial role.
Ukrainian Insurgent Army (UPA) has neither been a nazi or a neo-nazi organization. It fought against both National-Socialist Germany and Socialist Russia's USSR. Quoting Wikipedia,
During World War II, it was engaged in guerrilla warfare against the Soviet Union, the Polish Underground State, Kingdom of Romania, Communist Poland and Nazi Germany. — Wikipedia
Edit: the role of national-liberation movements during the WWII, including the OUN/UPA, is indeed complicated, see comments section below. For the sake of this question, the only accusation against Petro Vushko is his prosecution by the Russian regime.
The International Military Tribunal at Nuremberg did not indict OUN/UPA or its members on any crimes against humanity. The Tribunal papers contain a captured German document of 25 November 1941 that ordered (page 265) (also on Wikipedia):
"It has been ascertained that the Bandera Movement is preparing a revolt in the Reichskommissariat which has as its ultimate aim the establishment of an independent Ukraine." […]
A few minor points that may have prevented from finding sources about the person and the event:
- Ukrainians don't have names "Pyotr". It could have been a typo or a mistake made by Russian mass media referenced in the original question.
- There is no "Lvov" region in Ukraine. The town of Krakovets' is located in Yavoriv commune of Lviv region.