Prolific videographer Carlos Ferran, whose channel on YouTube, trainsruleandroll, is a shrine to all things Rio Grande, has yet another video (HD) that I can't pass up without passing along. He's got a good eye for railroad photography, and he keeps his finger on the pulse of the Joint Line.
I'll conclude this post by explaining what an officer special is and what the Joint Line is.
An officer special is a private passenger train of one to several cars owned by a railroad. Unlike a normal special, like the Union Pacific's Cheyenne Frontier Days Special, the trip is not ticketed for the public and it is not publicized anywhere except possibly to current customers and prospects. Therefore, as noted by Carlos, catching an officers special is a rarity. The power for the trains are typically one of the railroad's recent purchases, such as a GE ES44DC like BNSF 7689 in the video. The rolling stock is typically refurbished cars originally dating from the golden age of passenger rail.
The Joint Line runs from Denver southward through Pueblo, but the most appealing parts are from Castle Rock to just south of Colorado Springs. Between these points, the line climbs over the Palmer Divide, a montane ridge perpendicular to the Front Range that divides the Platte (Missouri) and Arkansas River basins. From the elevation in Denver to the summit of the pass at Palmer Lake and then down to Colorado Springs, the grade averages 1%, not Rocky Mountain railroading, but not exactly level. The dramatic mountain backdrop, the grades and easy access to most of the route from US 85 and I-25 makes the Joint Line a favorite for many railfans.