So, when i search for only one word among longplays, then it is perfectly fine. But when i type more than one word it only shows the 1st page properly, and trying to go to another page, it tells me there are 0 results.

For example, this is page 2 for the search "lava water": http://longplays.org/search.php?stype=longplays&stext=lava%2Bwater&method=OR&datelimit=0&fields=2&sort=datestamp&order=0&chars=50&forum_id=0&rowstart=10

In this URL, the space between the two words is replaced with %2B, this is the percent-encode for +.

However, if we replace %2B with either the actual + or %20 (the latter is the percent-encode for space), then it works perfectly fine: http://longplays.org/search.php?stype=longplays&stext=lava+water&method=OR&datelimit=0&fields=2&sort=datestamp&order=0&chars=50&forum_id=0&rowstart=10