"I have always just been a bass player that played the notes for the chord, but after watching you pentatonic scale dvd and reading Fretboard Theory I can see there's so much more to do. If I'm playing a song in the key of G can I play the G major scale up and down the 5 patterns and sound ok?"
Bass players apply guitar theory a little differently. This is because bassists are expected to establish the roots or tonal center of chords. Most of the time this consists of the actual root of the chord which is why many bass players don't think much beyond roots. But chords include other intervals and bass players can sometimes use the other intervals in place of the root.
For example, you could use a chord's third or fifth. You can see a list of bass songs that use all three intervals in Fretboard Theory page 86 Triads. When alternating between a chord's intervals you'll usually need to play the root first in order to establish the correct tonality. But on occasion bass players start chords on other intervals.
When playing a chord change, once the root has been established bass players have an opportunity to either play another interval from the chord or play a bit in an appropriate scale pattern. A good example of this is the song "Brown Eyed Girl" by Van Morrison. The bass always plays the root of each chord first, then follows with triad and scale movement leading to the next chord. It's a must learn song for bass players.
Other times songs are not based on chord changes but center around a single root. A good example of this is the song "Lowrider" by War. Everything centers around G using a blues mixture of minor pentatonic and mixoydian mode. The bass simply repeats a G minor pentatonic riff throughout the whole song. There is room for the bass to improvise with the scale, but it needs to get back to the root at the beginning of the 2 bar phrase in order to maintain the tonal center of the song.
