Bin Laden says the Prophet Mohammed wished martyrdom
But the clip, less than a minute long, is undated and correspondents say it may be re-run footage. Its authenticity also cannot be independently verified.
Osama Bin Laden is filmed outdoors in army fatigues and praises those who die in the name of "holy war".
The US Senate on Friday voted to double the reward on him to $50m (£24.5m).
Escaped militant
The clip of the al-Qaeda leader features in a 40-minute video on a militant web site that carries the logo of al-Qaeda's media wing.
The video mainly shows fighters paying tribute to fellow militants killed in Afghanistan.
Ayman al-Zawahiri's messages are usually more specific
Bin Laden says: "The happy [man] is the one that God has chosen to be a martyr."
He says the Prophet Mohammed "wished upon himself this status".
The last Bin Laden message - an audio tape in July 2006 - referred to identifiable events, including the situation in Somalia.
However, BBC security correspondent Frank Gardner says this time he makes no reference to recent events, unlike his strategic adviser Ayman al-Zawahiri, whose frequent videos are far more specific.
The bulk of the new video pays tribute to dead militants.
The self-proclaimed leader of al-Qaeda in Afghanistan, Mustafa Abu al-Yazeed, praises "courageous knights" who have answered the call "for the sake of God to kick out the occupier who has desecrated the pure soil of Afghanistan".
Another key figure identified on the video is Abu-Yahya al-Libbi, who escaped from US custody at the Bagram airbase in Afghanistan two years ago.
He says the Muslim world is "offering the best of its men and sacrificing the good of its sons... to protect its ideology".
On Friday, the US voted 87-1 to double the reward for the death or capture of Osama Bin Laden.
The vote came amid warnings that al-Qaeda had rebuilt its capacity to mount attacks and was trying to insert agents into the US.
A leaked draft of a new US intelligence report says al-Qaeda is at its strongest since just before the 11 September 2001 attacks on the US.
Osama bin Laden
Osama bin Laden has appeared in a new but undated video praising martyrdom. "The happy (person) is the one chosen by Allah to be a martyr," he could be seen saying.

The video had the insignia of the As-Sahab group, considered the media production house of Al-Qaeda. The background looked similar to that of older videos, known to have been filmed in Afghanistan.

The video, entitled "Winds of Paradise", features speeches by five suicide bombers and Al-Qaeda leadership. SITE Institute, a non-profit organization which tracks the online activity of terrorist organizations, said that the footage was old, but did not give an estimated date.