Peter Ustinov as Nero from 1951 film “Quo Vadis“.
The musical composition’s name is “Seikilos epitaph“.
Here are the lyrics he sings (thanks VeritasEtSeveritas):
Oh, lambent flame
Oh, force divine
Oh, omnivorous power:
Hail!
None is there swifter to bring destruction,
Yet carefree as a child
Thou with wild breezes playing
The old Troy shall be no more because of thee,
Thou harvester that strips the soil
For men to sow new crops
Oh, lambent flames
Oh, force divine
Oh, omnivorous power
Hail!