I feel it may be more mental placement of the phrase rather than a physical hurdle that's holding you back, Cliff.
Having said that, while it's useful to practise phrases in various positions, the one shown in the video around the 7th position (in G major although the audio has been sped up at some stage and does sound closer to Ab as played in your own video) seems much better suited for clean execution.
Regarding rpjazzguitar's post, yes we should be aware of where the primary 1st and 3rd downbeats are but as djg noted above, pros generally treat them as points of arrival not departure.
Contrary to expectations, consistently accenting them can actually destabilise our time feel or at least inhibit our sense of flow. Witness the 'stuck in the mud' result when audiences clap on the '1' and '3'. For that reason, most jazz musicians set their metronome in 4/4 tunes on beats '2' and '4' where it acts as a surrogate snare (most modern popular music forms feature this snare drum pattern). It helps create forward motion, a push and pull effect and tightens our groove.
However, the tempo of your Benson example is rapid and 8th notes now take on the role of 16ths. This means that beats '3' and '4' will be combined and felt as the new backbeat (or '2' at a slower tempo). As a result, if employing a metronome, we would practise this phrase with the click on beat '3' only - the equivalent of beats '2' and '4' at half the tempo.
Does this all square up with Benson's performance? Here it is with accents and slurs added. By the way, the green play line posted in the notated video is out of synch by an eighth note so listen rather than watch:
Picking up on djg's observations, notice that the first accent occurs on the 'and of 1' rather than the '1'. The next occurs on our new backbeat (remember that '3' in a bar of eighth note subdivisions is the equivalent of beat '2' when 16ths are the main subdivision). Importantly, it's also the apex of the whole phrase. Benson is a huge Charlie Parker fan and CP often places his accents in this manner.
Once again, the following accent comes on the 'and of 1' and in this instance, is slurred onto the next beat (yet another common device that prioritises the upbeat rather than downbeat). The penultimate accent lands on the last beat of that bar with the final one acting as a full stop to the whole phrase.
In closing, my advice if you want it to sound relaxed yet in the groove and swinging is to try playing the phrase in 7th position (or 10th if you're looking at playing it over Bb rhythm changes), follow djg's suggestions in #26 and have your metronome set to 130bpm clicking on beat '3' only (or beats '2' and '4' at 65bpm).
Best of luck and I hope all that makes sense.
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