Use a well-designed BNC footprint to ensure the BNC's signal landing pad achieves 75-Ω characteristic impedance. BNC suppliers usually provide recommendations on BNC footprint for best results.
Keep trace length short between the BNC and SDI_IO±. The trace routing for SDI_IO+ and SDI_IO– should be as symmetrical as possible, with approximately equal lengths and equal loading. The same is true for SDI_OUT+ and SDI_OUT–.