Downloading lectures from the internet and distributing them for da’wah purposes

The basic principle is that webmasters put this material on their websites for
people to listen to it and benefit from it. Some provide the means of downloading and recording them, so this is regarded as permission from them
to copy them. 

Based on this, there is nothing wrong with downloading these lectures and
recording them and distributing them to the youth and others, rather this is a beneficial and righteous deed, because it is calling people to
Allaah and cooperating in goodness. The Prophet (peace and blessings of Allaah be upon him) said: “Whoever calls people to right guidance
will have a reward like that of those who follow him, without that detracting from their reward in the slightest. And whoever calls people to
misguidance will have a burden of sin like that of those who follow him, without that detracting from their burden in the slightest.” Narrated by
Muslim, 2674, from the hadeeth of Abu Hurayrah. 

It is not permissible to try to download lectures from sites that do not allow
that, because that is transgressing against the rights of others who have written, compiled, invented etc (i.e., copyright); these are rights that
are protected, as it says in the statement of the Islamic Fiqh Council issued during its fifth conference held in Kuwait, 1-6 Jumada al-Awwal 1409
AH/ 10-15 December 1988 CE: 

Firstly: trade names, company names, trademarks, writings and inventions are all
the copyright of their owners or authors, which in modern practice have acquired monetary value. These rights are respected by sharee’ah and it is
not permissible to transgress against them. Copyright of authors and inventors is protected in Islam. 

….

Thirdly: the owner of these rights has the right to dispose of them and no one
should transgress against them. 

See Questions no 454
and 21927. 

And Allaah knows best.