How to Respond to a request for a letter of recommendation

In this video the author explains when to write a recommendation letter to some one. He says that one may often face this situation to write a recommendation letter to some one we know. He advises that you should write a recommendation letter about some one only if we think that they are good at what they do and if we really believe in them. He says not to write recommendation letter if there is any problem because there is a chance that we may loose our credibility by such an action. This video expresses the author's views on when to write a recommendation letter and when to say no.