The first fire in the Moria camp, which served as a reception area for migrants, destroyed the official part of the camp, which was home to about 4,000 people.
Another more than 8,000 residents have lived in tents and shacks erected around the camp, many of which were also destroyed.
The video shows an aerial view of the burned camp.
The island of Lesbos has been declared a state of emergency as a result of the fire.
About 3,500 camp residents were allowed to spend the night on a ferry brought to the port of Lesbos.
EU Vice-President Margaritis Schinas is due to visit Lesbos today before continuing his trip to Athens to meet with Prime Minister Kyriakos Mitsotak.
Mitsotakis said yesterday that the camp fire was the result of a "strong reaction" from camp residents to coronavirus testing.
The camp has confirmed 35 coronary infections in the past week.
Immigration Minister Notis Mitarachi said asylum seekers set the fire on fire because those who tested positive were quarantined.
Camp Moria has been home to more than 12,000 people, although it has been built for less than 3,000.
Authorities have long tried to build a new camp for Lesbos, but local residents have protested and teamed up with riot police to prevent construction work.
Austria does not intend to receive anyone
Following the Moria fire, Germany has called for a reform of the EU's asylum system.
"We urgently need to create a refugee reception system involving as many EU countries as possible and a common asylum and immigration system for the EU," said German European Minister Michael Roth.
Demonstrations were held yesterday across Germany demanding the release of Moria residents from the island.
Norway has pledged to receive 50 Syrians from Moria, and the EU and Greece have pledged to fund the relocation of 400 unaccompanied minors to mainland Greece.
Austrian Foreign Minister Alexander Schallenberg, on the other hand, rejected the idea of receiving asylum seekers from Moria.
- Shouting about redistribution cannot be a solution, he said in a television interview.
That, he said, would only lead to more human trafficking.
- If we empty Moria's camp, it will immediately be refilled.
Austria has provided aid worth one million euros, according to the minister, mainly tents and blankets.