I want to promote my site in this way: add source on FileTram and their crawler will add my files to their base and I will get more traffic.
But is it safe?
Of course it's safe, they just crawl your site, collect links and locate the files on their own. Afterall, everyone who will download through that link will somehow bring free traffic to your site. If I did not reply in full, you can read more on their help pages.