What is a mortgage contingency? - A mortgage contingency clause is a common buyer protection. You and your agent usually indicate that you will get a commitment to financing within a stated period of time. If you cannot do so, you can typically get your earnest money deposit back. That is how the contingency clause helps you.
How could waiving the mortgage ctg. help my case? - Waiving the opportunity to have a mortgage contingency may not make sense to you financially. However, anything you can do to remove possible restrictions to the seller will make your offer more attractive, effectively increasing your chances of having your offer accepted over others in a competitive market. In a seller's market where the homeowner has multiple parties interested in the property and multiple offers, he/she will likely not accept a contract with a mortgage contingency if there are other offers in play without one.