Filler words are a credibility killer. In this post, I link to the Six Minute blog for some answer to this problem.
No matter the language of the presentation, filler words like "um", "uh", "ah", "am", "eh"are a pain to the audience. Thankfully, Andrew Dlugan's Six Minute blog on public speaking is again active and full of great advice. In one of his latest post "How to Stop Um, Uh, and other Filler Words" he addresses the issue. I recommend you read it.