Spain's fast-rising populist Podemos party arguably got even more popular after a speech by its pony-tailed leader was remixed with a rap song to make a viral video.

Almost 400,000 people viewed a YouTube clip overlapping the voice of Pablo Iglesias, the 36-year-old leftist professor who is rocking the Spanish political scene, to the base of US rapper Dr. Dre's world famous Still D.R.E. song.

The video was uploaded on 31 January by user Dari and uses parts of the address Iglesias delivered the same day in Madrid's Puerta del Sol square to a crowd of up to 300,000 supporters.

The rally was the largest held by Podemos to date and came as the party is trying to capitalise on the electoral success of the radical-left Syriza coalition in Greece last month.

Both movements have witnessed a ballooning success thanks to the powerful mix of a charismatic leader promising change and the end of what they describe as Berlin-imposed austerity measures to economic crisis-torn southern European countries experiencing high levels of unemployment.

In the speech - and in the rap remix - Iglesias exalted last week's Greek vote that threw into power a "prime minister [Alexis Tsipras] who doesn't need to take the oath wearing a tie and whose first symbolic act was to pay tribute to the resistance heroes that opposed German occupation."

"Who said it's impossible? Who said that a government cannot change things?" he asked the crowd.

Adopting an informal dress style of jeans and rolled up shirt sleeves, Iglesias has led Podemos ("We Can") from the fringe dream of a handful of activists to a mainstream party that, according to opinion polls could snatch a victory at the upcoming general elections.

The Pablo Iglesias feat. Dr Dre video also proved to be a success and was swiftly followed by a 7-track album.