I am using Ubuntu 16.04 and i am trying to play .swf files, i have tried playing them with gnash but i am not able to seek the video forward or rewind it.
Please suggest me a good app for same with option for seeking the video play too.

Please help me out.

Try vlc, I believe I have played SWF files with it in the past.

I tend towards mpv. Although some formats lack indexing and you have to force it (--index=recreate, formerly --forceidx) to have the option to skip around. But doing this adds a delay before playback while it builds an index. I find it more convenient to re-encode the video for those things, if it's something I'll watch more than once and it's longer than ten minutes.

Another memory recall is that SWF means like Shock Wave Flash. Therefore I recall using a browser to view these. The ones I was looking at were quick animations like what you see with an animated GIF, or at least this was my one-time experience with these types of files. I think the only issue might be if the browser has a shock wave add-on, or allows this capability.

I am not able to seek the video, it is glitchy in vlc the video is paused and audio runs in the background.

Once again, they appear to be Shock Wave Flash files and I'm not sure this format is highly accepted or used.

I have viewed some small ones in a browser, however that was also a case where it a joke forwarded to me, I viewed it and had the appropriate amusement, and then moved on and never worried again about that format.

I think what happened also was that once I had used my browser for it, the system assumed this was my default choice and used Firefox to open them thereafter.

Try the browser, however I don't believe this format is very useful. Perhaps just my humble opinion there, but that's all I have about the topic.

Shadow_7 may be more helpful with their point about a different format, and then you should seek a way to convert the file to something more common, such as MOV, MP4, AVI, MPEG, etc.

SWF is only fully supported by Adobe's own software in the Google Chrome browser. All other Adobe support, like the browser flash plug-in and Adobe Integrated Runtime, are no longer available for Linux. Gnash tries to support the format, but that project is languishing and has always been hampered by lack of date on the format.

sagxam, one-sentence replies beget one-sentence replies:
there used to be a standalone flashplayer.
try if you can find it.

You could try the pepperflash plugin. I have seen swf files that won't play on anything Linux. In the past they weren't important enough for me to really care. So, I always just tossed them.

If I can't play it in Linux I don't need it! I was once on eBay. I contacted tech support. They asked me to try a different browser. I said, "If it doesn't work with firefox I don't need it."

That's pretty much my attitude. If they can't make it work with the standard tools, it's not worth my time.