Motor & Trans Mount Deflection - Normal
This is just the Motor and Trans rubber mounts Deflecting under load. When you accelerate hard it should pull (likely to the right) just a little, and the other way when you let the clutch out downshifting. If you are driving hard and grabbing gears, this effect should be more pronounced.
The only thing that would cause a continued vibration/shudder is an imbalanced drive-shaft. You can check this by observing how much vibe you have going slowly, like 20mph. As you increase speed the shudder will also become faster, go all the way up to 70. Then put in the clutch and Hold it in so the motor goes to idle, while your coasting at 65+
If you still have the vibe fast, while coasting 65+ with motor at idle your driveline is a little out of balance - not a big deal to fix, but you have to pull the exhaust to get it out - or let the dealer do it.