Developing a question answering (Q/A) system involves in integrating abundant linguistic resources such as syntactic parsers, named entity recognizers which are not only impose time cost but also unavailable in other languages. Ranking-based approaches take the advantage of both efficiency and multilingual portability but most of them bias to high frequent words. In this paper, we propose a new passage ranking algorithm for extending textQ/A toward videoQ/A based on searching lexical information in videos. This method takes both N-gram match and word density into account and finds the optimal match sequence using dynamic programming techniques. Besides, it is very efficient to handle real time tasks for online video question answering. We evaluated our method with 150 actual user's questions on the 45GB video collections. Nevertheless, four well-known but multilingual portable ranking approaches were adopted to compare. Experimental results show that our method outperforms the second best approach with relatively 25.64% MRR score.