PowerPoint online file converters

The problems with many on-line conversion sites is that they require registration - which of course means you may be getting a ton of junk email. I tried www.pptx2ppt.com and it seemed to be clean. It did as advertised. It converted files from one format to another without registration and the the converted file was free of viruses according to AVG. I converted a. Docx to a. Doc file without problems. However when I converted a. Odp file to. Pptx (powerpoint) - it converted fine - but the new, pptx file would not play all of the videos I loaded into my presentation. I am not sure if the failure to play videos was their fault or mine. I was pushing the limits of the impress presentation program by embedding videos- this may be beyond the limits of the program - perhaps my error. I would give this site 5 stars - if I was sure the error was my fault - and not theirs. Some other people need to check this site out and see how they do on file conversion. I will try this site again in future and raise the rating to 5 stars if other conversions go without a hitch.